Research ArticleFailure Mechanism Analysis and Support Design forDeep Composite Soft Rock Roadway A Case Study of theYangcheng Coal Mine in China

Bangyou Jiang1 Lianguo Wang1 Yinlong Lu1 Shitan Gu2 and Xiaokang Sun1

1State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116 China2College of Mining and Safety Engineering Shandong University of Science and Technology Qingdao 266590 China

Correspondence should be addressed to Lianguo Wang lgwangcumteducn

Received 7 April 2015 Revised 29 May 2015 Accepted 3 June 2015

Academic Editor Alicia Gonzalez-Buelga

Copyright copy 2015 Bangyou Jiang et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

This paper presented a case study of the failure mechanisms and support design for deep composite soft rock roadway in theYangcheng Coal Mine of China Many experiments and field tests were performed to reveal the failure mechanisms of theroadway It was found that the surrounding rock of the roadway was HJS complex soft rock that was characterized by poor rockquality widespread development of joint fissures and an unstable creep property The major horizontal stress which was almostperpendicular to the roadway was 159 times larger than the vertical stress The weak surrounding rock and high tectonic stresswere the main internal causes of roadway instabilities and the inadequate support was the external cause Based on the failuremechanism a new support design was proposed that consisted of bolting cable metal mesh shotcrete and grouting A fieldexperiment using the new design was performed in a roadway section approximately 100m long Detailed deformationmonitoringwas conducted in the experimental roadway sections and sections of the previous roadway The monitoring results showed thatdeformations of the roadway with the new support design were reduced by 85ndash90 compared with those of the old design Thissuccessful case provides an important reference for similar soft rock roadway projects

1 Introduction

Support for a soft rock roadway especially for deep high-stressed composite soft rock roadways is a worldwide prob-lem [1] Composite soft rock is characterized by a broken-rock structure low rock strength intense water swelling andrheological response [2 3] In a complicated geomechanicalenvironment (ie high in-situ stress high ground tempera-ture high osmotic pressure and strong mining disturbance)many roadways in deep coal mines with weak surroundingrocks experience severe deformations and failure whichnot only reduces the functionality of the roadway but alsoendangers the safety of the mine personnel

Recently numerous studies have been performed on thefailure mechanisms of deep soft rock roadways He et alperformed an experiment and field investigation of the

roadway of a loaded-car line that was seriously destroyedin the Xingrsquoan Coal Mine China and found that the largeburied depth and strong tectonic stress caused its failure[4] Deep soft rocks are often cut by various weak planes(eg joint and bedding) [5] Under high in-situ stresses ashear slip will appear along these weak planes which couldloosen the structure of the surrounding rock and eventuallycaused an unstable failure of the roadway [6ndash8] Seedsmanand Yuan discussed the failure mechanisms of deep soft rockroadways [9 10]Their studies showed that low rock strengthand broken-rock structure lead to huge plastic deformationsandfinally failureWu et al obtained the same conclusion [11]In addition Huang et al presented the idea that in a high-stress environment the soft rock had a strong rheologicalresponse and the rheological zone persistently developedtoward the interior of the rock surrounding the roadway

Hindawi Publishing CorporationShock and VibrationVolume 2015 Article ID 452479 14 pageshttpdxdoiorg1011552015452479

2 Shock and Vibration

which lead to instability [12] However different deep softrock roadways have different failure mechanisms because ofthe complicated changing engineering geological conditionsBased on a survey of a large number of documents Shenconcluded that various roadway failure mechanisms couldbe classified into six types beam failure joint controlledrock falls roof sag guttering and shear failure skin failureand rib failure [1] This classification method has great valuefor applications and instructions In general a complicatedgeomechanical environment andweakmechanical propertiesof the surrounding rock are the original external and internalcauses respectively of a deep soft rock roadway failure

Research on the failuremechanisms of a roadway is a pre-requisite of realizing the ultimate goal of a reasonable supportdesign Currently bolt anchor cable grouting yieldable steelsets and combined supporting systems are widely employedin soft rock roadways in deep coal mines but the mostoptimal supporting system is arguable Bolting and boltingcombined with metal net and shotcrete are extensively usedin many countries such as the United States of America andAustralia whereas in Germany Poland and other Europeancountries U-shaped steel sets are commonly used as themainsupportmethods [13] Because of the reasonable cross sectionshape and high strength yieldable U-shaped steel supportsare always used to maintain the stability of roadways inloose and broken-rock strata [14] However the high cost andcomplex process of installing these supports are themain dis-advantages and fatal flaws of this support type Recently theyielding bolts support has become very popularThis methodworks by adding a yielding tube to the bolts [15] Althoughthis yielding support can adapt well to the deformation andpressure of a soft rock roadway its strength and yieldingcapacity are limited The yielding bolts support is seldomused in a large deformation broken soft rock roadway [16]Wang et al proposed a combined bolt and grouting supportto control large deformations of a soft rock roadway andachieved good control of the deformations [17] A new andeffective support technology the bolt-grouting support hasdeveloped rapidly and has been widely employed in soft rockroadways and tunnel engineering [18ndash20] Moreover therearemany other support technologies for soft rock such as theconcrete-filled steel tubular stent [21] constant resistance andlarge deformation bolts [22] and other combined supporttechnologies [23ndash25] However these support technologiesare unable to restrain the loose and broken rock surroundinga deep high-stress complicated soft rock roadway

So the failure mechanisms and support technologiesof a soft rock roadway under complicated conditions havebeen the focus of research in mining engineering and otherrelated fields This paper reports a case study of the failuremechanisms and support design for a deep composite softrock roadway in the Yangcheng Coal Mine in ShandongProvince China In this paper a large number of experimentsand field tests were performed and a mechanical model wasdeveloped Furthermore based on the failuremechanism andcharacteristic of the roadway a new optimal support was pro-posed and more reasonable parameters were designed Theresearch results provide a significant reference for supportdesign for similar roadway engineering projects

Lithologicalgeologicalcolumn

ThicknessLithology(m) Lithology description

543 Mudstone Contained No 2 coal seam

1051 Medium-grainedsandstone

Shale cementation existingcarbonaceous texture bedding

development

476 Gray mudstone

1059

778 No 3 coal seamMassive structure joint

development

06Massive structure common

slip surface

27 Fine sandstone and siltstoneinterbedded

68

Mudstone

Mudstone

Mudstone

Finesandstone

Finesandstone

Fine sandstone and siltstoneinterbedded wavy bedding

development

Massive structure silty

the thickness of which is 045m

Figure 1 Strata histogram of 3 coal seam roof and floor

2 Geology and Engineering Background

Located in the Jibei diggings in Shandong Province theYangcheng Coal Mine covers a mining area of 46 km2 (22sim67 km wide from east to west and 105 km long from northto south) with 153 million tons of recoverable reserves andan estimated production capacity of 24 million ta Theminus650 main roadway in the south wing was the horizontaldevelopment roadway that was responsible for ventilationand transportation to mining areas in the south wing for thenext 12 years of production Obviously this roadway was veryimportant to the whole coal mine Due to faults the roadwaycrossed overNo 3 coal seam and otherweak strata on the roofand floor (Figure 1) which extremely reduced the strengthand integrity of the surrounding rock

The buried depth of themain roadway was approximately700m The cross section was a semicircle arch with straightwallsThe walls were 18m high the arch was 24m high andthe net width of the roadway was 48m Primarily bolts com-bined with anchor cables and metal mesh were used as thepermanent support to control the surrounding rock Threemonths after excavation the roadway is seriously distortedand the cross section area of some sections shrank by morethan 80 (Figure 2) Subsequently the damaged roadway hadbeen repaired and reinforced Based on the original supportseven grouting bolts with a diameter of 26mm and a lengthof 25m were evenly installed in the whole cross section at aninterval of 2400mm along the roadway axis U-shaped steelsheds with a width of 4800mm and a height of 4765mmwereplaced at an interval of 1200mm Furthermore an invertedarch that matched the U-shaped steel sheds was used andconcrete was poured to 525mm thickness The supportdesign is presented in Figure 3 However the main roadwaystill suffered large deformations (Figure 4) Repeated repairsand reinforcements lead to the vicious circle of ldquoexcavation-repair-failurerdquo Therefore it is urgent to thoroughly study thefailure mechanisms and optimize a support design

Shock and Vibration 3

Contour of primaryroadway

Contour of damaged roadway

10m

26m

Figure 2 Large deformation of the roadway

Shotcretelayer

U-shapedsteel sheds

Concrete

Inverted arch

Lap joint

Angle steel

4800 4200

R2400

500

150

Φ20 times 2200mm bolt

Φ178 times 6400mm cable

Figure 3 The old supporting design of the roadway

3 Experiments and Field Tests

31 Physical and Mechanical Properties The rock qualitydesignation (RQD) is an index that provides a quantitativejudgment of the rock mass quality which can be obtainedfrom drill cores [26 27] Core drilling was performed infour representative locations (1 2 3 and 4) in themain roadway as shown in Figure 5 The RQD of the fourlocations were 219 214 431 and 258 respectivelyThe descriptive statistics of the RQD samples are presentedin Table 1 From the statistics in Table 1 the rock qualityat locations 1 and 2 was very poor (Classification V)Similarly the rock quality at location 3 and 4 was poor(Classification VI) This indicated that the integrity of therock surrounding the main roadway was low which allowedwide development of joint fissures

Rock samples were divided into siltstone fine sandstonemedium-grained sandstone and mudstone according to

Table 1 Classification criterion of rock quality by the RQD [26 27]

RQD () Classification Rock qualitylt25 V Very poor25ndash50 IV Poor50ndash75 III Fine75ndash90 II Good90ndash100 I Excellent

their lithological characteristics Conventional physical andmechanical tests were conducted on rock samples using aMTS 81502 rock servo-hydraulic machine Test results arelisted in Table 2 The D and E mudstone samples are veryweak They are typical soft rock samples due to their lowuniaxial compressive strengths (2413MPa and 2305MPa)and tensile strengths (163MPa and 222MPa) The A minusminusC sandstone samples have high strength with uniaxialcompressive strengths greater than 30MPa The uniaxialcompressive strength of theA siltstone sample is 4746MPaHowever because of the wide development of joint fissuresin the surrounding rock the whole engineering rock mass issignificantly distorted under the action of engineering forcestherefore this sample has the characteristics of a jointed softrock

To study the softening characteristics of water in the sur-rounding rock a saturated water content test was conductedon the surrounding rock sample The uniaxial compressivestrengths of the water-saturated samples are presented inTable 2The uniaxial compressive strength of water-saturatedsamples decreases significantly The softening coefficient oftheEmudstone in the water-saturated condition is 028TheDmudstone disintegrated in water (Figure 6) Rock samplescontain expansible hydrophilic clay minerals that quicklyabsorb water molecules when the samples are soaking inwater which will destroy the microstructure decrease thestrength and even disintegrate the rock samples

In addition uniaxial creep tests of the rock sampleswere performed using a multistep incremental loading Theloading rate of each stage was 40Ns and the duration ofeach stage was approximately 24 h Some results of the creeptest are shown in Figure 7 The creep tests demonstratedthat the surrounding rock in the main roadway has anunstable creep property and the critical strength of theunstable creep deformation of different rock samples rangeswithin 12sim20MPa Based on the comprehensive analysis thesurrounding rock in the main roadway of the YangchengCoal Mine is an HJS complex soft rock with combinedcharacteristics of a jointed soft rock expansible soft rock andhigh-stress soft rock [2]

32 In Situ Stresses

321 Gravity Stress Field The overall buried depth of themain roadway is approximately 700m The mean volume-weight of the overlying rock is approximately 25KNm3 sothe gravity stress is 175MPa higher than the strength of

4 Shock and Vibration

Table 2 Physical and mechanical parameters of surrounding rocks

Serialnumber Lithology

Natural specimens Saturated specimens

Bulkdensity(KNsdotm3)

Uniaxialcompressivestrength(MPa)

Tensilestrength(MPa)

Poissonrsquosratio

Elasticmodulus(GPa)

Uniaxialcompressivestrength(MPa)

Softeningcoefficient

A Siltstone 2570 4746 582 025 589 2278 048B Fine sandstone 2516 3185 376 013 523 1720 054

C Medium-grainedsandstone 2461 3014 449 018 523 2200 073

D Mudstone 2465 2413 163 011 310 mdash mdashE Mudstone 2575 2305 222 010 430 645 028

(a) Shed leg twisted (b) Floor heaved seriously

(c) Roof fractured (d) Connection failure

Figure 4 Deformation and failure of the roadway after repairing

minus700

minus700

minus560

minus580

minus600

minus620

minus640

minus660

minus600

minus680

minus660

minus580

minus560

minus680

minus660

minus660

minus640

minus620 72458060176

12

4

3

1307 working face

minus650 main roadway in the south wingMonitoring sections123 4 5

15∘

9∘

N1203∘ 51

998400 11998400998400 E100m trial raodway

70∘H

=0sim25m

70∘H = 0 sim

18m

CF6ang

DF54 ang

Figure 5 The locations of boreholes 1sim4

Shock and Vibration 5

4h 12h

24h 2d

Figure 6 Water-induced weakening process of mudstone

the surrounding rock The critical strength of the unstablecreep deformation of different surrounding rock strata is 12sim20MPa which is easily exceeded by the surrounding rockstress because of roadway excavation This explains why thesurrounding rock has large nonlinear flow deformations afterroadway excavation

322 Tectonic Stress Field Based on the tectonic stress testresults for the Yangcheng CoalMine [28] themajor principalstress in the in situ stress field is the horizontal stressThe azimuth angle of the maximum principal horizontalstress is 1123∘ The maximum principal horizontal stressis 2781MPa or 159 times greater than the vertical stressand 192 times greater than the minimum principal hori-zontal stress (1447MPa) The angle between the axis of themain roadway and maximum principal horizontal stress is877∘ The influence of the horizontal stress on the mainroadway during excavation can lead to severe failure of theroadway

33 Broken-Rock Zone and Failure Characteristics Thebroken-rock zone and failure characteristics were detected

by a borehole TV in several typical sections of the main softrock roadway (Figure 8) The field borehole TV detectiondiscovered that the rock surrounding the main roadway canbe divided into intact crack and fracture zones according tothe degree of failure [29] as shown in Figure 9 An intact zoneis defined as a region in which no fissures are observed alonga continuous distance of 30 cm of the borehole A crack zoneis defined as a region that contains 1-2 sets of fissures alonga continuous distance of 30 cm of the borehole A fracturezone is a region that contains three ormore fissures or evidentfracture along a continuous distance of 30 cm of the borehole

The surrounding rock failure of the main air returnroadway was analyzed based on these definitions of zonesGenerally speaking the surrounding rock is seriously dis-torted with a large broken-rock zone (approximately 2sim3mand even reaching 5m in some places) and discontinuousasymmetrical failure Many crack zones and fracture zonesare observed within a 3m range of the surrounding rockWhen the borehole depth exceeds 3m the crack zone andintact zone occur alternately As the borehole goes deeper thelength of the intact zone gradually increasesThe depth of thesurrounding rock failure is very large and the crack zone stillcan be detected at a depth of 8ndash10m

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

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2 Shock and Vibration

which lead to instability [12] However different deep softrock roadways have different failure mechanisms because ofthe complicated changing engineering geological conditionsBased on a survey of a large number of documents Shenconcluded that various roadway failure mechanisms couldbe classified into six types beam failure joint controlledrock falls roof sag guttering and shear failure skin failureand rib failure [1] This classification method has great valuefor applications and instructions In general a complicatedgeomechanical environment andweakmechanical propertiesof the surrounding rock are the original external and internalcauses respectively of a deep soft rock roadway failure

Research on the failuremechanisms of a roadway is a pre-requisite of realizing the ultimate goal of a reasonable supportdesign Currently bolt anchor cable grouting yieldable steelsets and combined supporting systems are widely employedin soft rock roadways in deep coal mines but the mostoptimal supporting system is arguable Bolting and boltingcombined with metal net and shotcrete are extensively usedin many countries such as the United States of America andAustralia whereas in Germany Poland and other Europeancountries U-shaped steel sets are commonly used as themainsupportmethods [13] Because of the reasonable cross sectionshape and high strength yieldable U-shaped steel supportsare always used to maintain the stability of roadways inloose and broken-rock strata [14] However the high cost andcomplex process of installing these supports are themain dis-advantages and fatal flaws of this support type Recently theyielding bolts support has become very popularThis methodworks by adding a yielding tube to the bolts [15] Althoughthis yielding support can adapt well to the deformation andpressure of a soft rock roadway its strength and yieldingcapacity are limited The yielding bolts support is seldomused in a large deformation broken soft rock roadway [16]Wang et al proposed a combined bolt and grouting supportto control large deformations of a soft rock roadway andachieved good control of the deformations [17] A new andeffective support technology the bolt-grouting support hasdeveloped rapidly and has been widely employed in soft rockroadways and tunnel engineering [18ndash20] Moreover therearemany other support technologies for soft rock such as theconcrete-filled steel tubular stent [21] constant resistance andlarge deformation bolts [22] and other combined supporttechnologies [23ndash25] However these support technologiesare unable to restrain the loose and broken rock surroundinga deep high-stress complicated soft rock roadway

So the failure mechanisms and support technologiesof a soft rock roadway under complicated conditions havebeen the focus of research in mining engineering and otherrelated fields This paper reports a case study of the failuremechanisms and support design for a deep composite softrock roadway in the Yangcheng Coal Mine in ShandongProvince China In this paper a large number of experimentsand field tests were performed and a mechanical model wasdeveloped Furthermore based on the failuremechanism andcharacteristic of the roadway a new optimal support was pro-posed and more reasonable parameters were designed Theresearch results provide a significant reference for supportdesign for similar roadway engineering projects

Lithologicalgeologicalcolumn

ThicknessLithology(m) Lithology description

543 Mudstone Contained No 2 coal seam

1051 Medium-grainedsandstone

Shale cementation existingcarbonaceous texture bedding

development

476 Gray mudstone

1059

778 No 3 coal seamMassive structure joint

development

06Massive structure common

slip surface

27 Fine sandstone and siltstoneinterbedded

68

Mudstone

Mudstone

Mudstone

Finesandstone

Finesandstone

Fine sandstone and siltstoneinterbedded wavy bedding

development

Massive structure silty

the thickness of which is 045m

Figure 1 Strata histogram of 3 coal seam roof and floor

2 Geology and Engineering Background

Located in the Jibei diggings in Shandong Province theYangcheng Coal Mine covers a mining area of 46 km2 (22sim67 km wide from east to west and 105 km long from northto south) with 153 million tons of recoverable reserves andan estimated production capacity of 24 million ta Theminus650 main roadway in the south wing was the horizontaldevelopment roadway that was responsible for ventilationand transportation to mining areas in the south wing for thenext 12 years of production Obviously this roadway was veryimportant to the whole coal mine Due to faults the roadwaycrossed overNo 3 coal seam and otherweak strata on the roofand floor (Figure 1) which extremely reduced the strengthand integrity of the surrounding rock

The buried depth of themain roadway was approximately700m The cross section was a semicircle arch with straightwallsThe walls were 18m high the arch was 24m high andthe net width of the roadway was 48m Primarily bolts com-bined with anchor cables and metal mesh were used as thepermanent support to control the surrounding rock Threemonths after excavation the roadway is seriously distortedand the cross section area of some sections shrank by morethan 80 (Figure 2) Subsequently the damaged roadway hadbeen repaired and reinforced Based on the original supportseven grouting bolts with a diameter of 26mm and a lengthof 25m were evenly installed in the whole cross section at aninterval of 2400mm along the roadway axis U-shaped steelsheds with a width of 4800mm and a height of 4765mmwereplaced at an interval of 1200mm Furthermore an invertedarch that matched the U-shaped steel sheds was used andconcrete was poured to 525mm thickness The supportdesign is presented in Figure 3 However the main roadwaystill suffered large deformations (Figure 4) Repeated repairsand reinforcements lead to the vicious circle of ldquoexcavation-repair-failurerdquo Therefore it is urgent to thoroughly study thefailure mechanisms and optimize a support design

Shock and Vibration 3

Contour of primaryroadway

Contour of damaged roadway

10m

26m

Figure 2 Large deformation of the roadway

Shotcretelayer

U-shapedsteel sheds

Concrete

Inverted arch

Lap joint

Angle steel

4800 4200

R2400

500

150

Φ20 times 2200mm bolt

Φ178 times 6400mm cable

Figure 3 The old supporting design of the roadway

3 Experiments and Field Tests

31 Physical and Mechanical Properties The rock qualitydesignation (RQD) is an index that provides a quantitativejudgment of the rock mass quality which can be obtainedfrom drill cores [26 27] Core drilling was performed infour representative locations (1 2 3 and 4) in themain roadway as shown in Figure 5 The RQD of the fourlocations were 219 214 431 and 258 respectivelyThe descriptive statistics of the RQD samples are presentedin Table 1 From the statistics in Table 1 the rock qualityat locations 1 and 2 was very poor (Classification V)Similarly the rock quality at location 3 and 4 was poor(Classification VI) This indicated that the integrity of therock surrounding the main roadway was low which allowedwide development of joint fissures

Rock samples were divided into siltstone fine sandstonemedium-grained sandstone and mudstone according to

Table 1 Classification criterion of rock quality by the RQD [26 27]

RQD () Classification Rock qualitylt25 V Very poor25ndash50 IV Poor50ndash75 III Fine75ndash90 II Good90ndash100 I Excellent

their lithological characteristics Conventional physical andmechanical tests were conducted on rock samples using aMTS 81502 rock servo-hydraulic machine Test results arelisted in Table 2 The D and E mudstone samples are veryweak They are typical soft rock samples due to their lowuniaxial compressive strengths (2413MPa and 2305MPa)and tensile strengths (163MPa and 222MPa) The A minusminusC sandstone samples have high strength with uniaxialcompressive strengths greater than 30MPa The uniaxialcompressive strength of theA siltstone sample is 4746MPaHowever because of the wide development of joint fissuresin the surrounding rock the whole engineering rock mass issignificantly distorted under the action of engineering forcestherefore this sample has the characteristics of a jointed softrock

To study the softening characteristics of water in the sur-rounding rock a saturated water content test was conductedon the surrounding rock sample The uniaxial compressivestrengths of the water-saturated samples are presented inTable 2The uniaxial compressive strength of water-saturatedsamples decreases significantly The softening coefficient oftheEmudstone in the water-saturated condition is 028TheDmudstone disintegrated in water (Figure 6) Rock samplescontain expansible hydrophilic clay minerals that quicklyabsorb water molecules when the samples are soaking inwater which will destroy the microstructure decrease thestrength and even disintegrate the rock samples

In addition uniaxial creep tests of the rock sampleswere performed using a multistep incremental loading Theloading rate of each stage was 40Ns and the duration ofeach stage was approximately 24 h Some results of the creeptest are shown in Figure 7 The creep tests demonstratedthat the surrounding rock in the main roadway has anunstable creep property and the critical strength of theunstable creep deformation of different rock samples rangeswithin 12sim20MPa Based on the comprehensive analysis thesurrounding rock in the main roadway of the YangchengCoal Mine is an HJS complex soft rock with combinedcharacteristics of a jointed soft rock expansible soft rock andhigh-stress soft rock [2]

32 In Situ Stresses

321 Gravity Stress Field The overall buried depth of themain roadway is approximately 700m The mean volume-weight of the overlying rock is approximately 25KNm3 sothe gravity stress is 175MPa higher than the strength of

4 Shock and Vibration

Table 2 Physical and mechanical parameters of surrounding rocks

Serialnumber Lithology

Natural specimens Saturated specimens

Bulkdensity(KNsdotm3)

Uniaxialcompressivestrength(MPa)

Tensilestrength(MPa)

Poissonrsquosratio

Elasticmodulus(GPa)

Uniaxialcompressivestrength(MPa)

Softeningcoefficient

A Siltstone 2570 4746 582 025 589 2278 048B Fine sandstone 2516 3185 376 013 523 1720 054

C Medium-grainedsandstone 2461 3014 449 018 523 2200 073

D Mudstone 2465 2413 163 011 310 mdash mdashE Mudstone 2575 2305 222 010 430 645 028

(a) Shed leg twisted (b) Floor heaved seriously

(c) Roof fractured (d) Connection failure

Figure 4 Deformation and failure of the roadway after repairing

minus700

minus700

minus560

minus580

minus600

minus620

minus640

minus660

minus600

minus680

minus660

minus580

minus560

minus680

minus660

minus660

minus640

minus620 72458060176

12

4

3

1307 working face

minus650 main roadway in the south wingMonitoring sections123 4 5

15∘

9∘

N1203∘ 51

998400 11998400998400 E100m trial raodway

70∘H

=0sim25m

70∘H = 0 sim

18m

CF6ang

DF54 ang

Figure 5 The locations of boreholes 1sim4

Shock and Vibration 5

4h 12h

24h 2d

Figure 6 Water-induced weakening process of mudstone

the surrounding rock The critical strength of the unstablecreep deformation of different surrounding rock strata is 12sim20MPa which is easily exceeded by the surrounding rockstress because of roadway excavation This explains why thesurrounding rock has large nonlinear flow deformations afterroadway excavation

322 Tectonic Stress Field Based on the tectonic stress testresults for the Yangcheng CoalMine [28] themajor principalstress in the in situ stress field is the horizontal stressThe azimuth angle of the maximum principal horizontalstress is 1123∘ The maximum principal horizontal stressis 2781MPa or 159 times greater than the vertical stressand 192 times greater than the minimum principal hori-zontal stress (1447MPa) The angle between the axis of themain roadway and maximum principal horizontal stress is877∘ The influence of the horizontal stress on the mainroadway during excavation can lead to severe failure of theroadway

33 Broken-Rock Zone and Failure Characteristics Thebroken-rock zone and failure characteristics were detected

by a borehole TV in several typical sections of the main softrock roadway (Figure 8) The field borehole TV detectiondiscovered that the rock surrounding the main roadway canbe divided into intact crack and fracture zones according tothe degree of failure [29] as shown in Figure 9 An intact zoneis defined as a region in which no fissures are observed alonga continuous distance of 30 cm of the borehole A crack zoneis defined as a region that contains 1-2 sets of fissures alonga continuous distance of 30 cm of the borehole A fracturezone is a region that contains three ormore fissures or evidentfracture along a continuous distance of 30 cm of the borehole

The surrounding rock failure of the main air returnroadway was analyzed based on these definitions of zonesGenerally speaking the surrounding rock is seriously dis-torted with a large broken-rock zone (approximately 2sim3mand even reaching 5m in some places) and discontinuousasymmetrical failure Many crack zones and fracture zonesare observed within a 3m range of the surrounding rockWhen the borehole depth exceeds 3m the crack zone andintact zone occur alternately As the borehole goes deeper thelength of the intact zone gradually increasesThe depth of thesurrounding rock failure is very large and the crack zone stillcan be detected at a depth of 8ndash10m

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

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Submit your manuscripts athttpwwwhindawicom

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Shock and Vibration

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Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Chemical EngineeringInternational Journal of Antennas and

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Navigation and Observation

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DistributedSensor Networks

International Journal of

Shock and Vibration 3

Contour of primaryroadway

Contour of damaged roadway

10m

26m

Figure 2 Large deformation of the roadway

Shotcretelayer

U-shapedsteel sheds

Concrete

Inverted arch

Lap joint

Angle steel

4800 4200

R2400

500

150

Φ20 times 2200mm bolt

Φ178 times 6400mm cable

Figure 3 The old supporting design of the roadway

3 Experiments and Field Tests

31 Physical and Mechanical Properties The rock qualitydesignation (RQD) is an index that provides a quantitativejudgment of the rock mass quality which can be obtainedfrom drill cores [26 27] Core drilling was performed infour representative locations (1 2 3 and 4) in themain roadway as shown in Figure 5 The RQD of the fourlocations were 219 214 431 and 258 respectivelyThe descriptive statistics of the RQD samples are presentedin Table 1 From the statistics in Table 1 the rock qualityat locations 1 and 2 was very poor (Classification V)Similarly the rock quality at location 3 and 4 was poor(Classification VI) This indicated that the integrity of therock surrounding the main roadway was low which allowedwide development of joint fissures

Rock samples were divided into siltstone fine sandstonemedium-grained sandstone and mudstone according to

Table 1 Classification criterion of rock quality by the RQD [26 27]

RQD () Classification Rock qualitylt25 V Very poor25ndash50 IV Poor50ndash75 III Fine75ndash90 II Good90ndash100 I Excellent

their lithological characteristics Conventional physical andmechanical tests were conducted on rock samples using aMTS 81502 rock servo-hydraulic machine Test results arelisted in Table 2 The D and E mudstone samples are veryweak They are typical soft rock samples due to their lowuniaxial compressive strengths (2413MPa and 2305MPa)and tensile strengths (163MPa and 222MPa) The A minusminusC sandstone samples have high strength with uniaxialcompressive strengths greater than 30MPa The uniaxialcompressive strength of theA siltstone sample is 4746MPaHowever because of the wide development of joint fissuresin the surrounding rock the whole engineering rock mass issignificantly distorted under the action of engineering forcestherefore this sample has the characteristics of a jointed softrock

To study the softening characteristics of water in the sur-rounding rock a saturated water content test was conductedon the surrounding rock sample The uniaxial compressivestrengths of the water-saturated samples are presented inTable 2The uniaxial compressive strength of water-saturatedsamples decreases significantly The softening coefficient oftheEmudstone in the water-saturated condition is 028TheDmudstone disintegrated in water (Figure 6) Rock samplescontain expansible hydrophilic clay minerals that quicklyabsorb water molecules when the samples are soaking inwater which will destroy the microstructure decrease thestrength and even disintegrate the rock samples

In addition uniaxial creep tests of the rock sampleswere performed using a multistep incremental loading Theloading rate of each stage was 40Ns and the duration ofeach stage was approximately 24 h Some results of the creeptest are shown in Figure 7 The creep tests demonstratedthat the surrounding rock in the main roadway has anunstable creep property and the critical strength of theunstable creep deformation of different rock samples rangeswithin 12sim20MPa Based on the comprehensive analysis thesurrounding rock in the main roadway of the YangchengCoal Mine is an HJS complex soft rock with combinedcharacteristics of a jointed soft rock expansible soft rock andhigh-stress soft rock [2]

32 In Situ Stresses

321 Gravity Stress Field The overall buried depth of themain roadway is approximately 700m The mean volume-weight of the overlying rock is approximately 25KNm3 sothe gravity stress is 175MPa higher than the strength of

4 Shock and Vibration

Table 2 Physical and mechanical parameters of surrounding rocks

Serialnumber Lithology

Natural specimens Saturated specimens

Bulkdensity(KNsdotm3)

Uniaxialcompressivestrength(MPa)

Tensilestrength(MPa)

Poissonrsquosratio

Elasticmodulus(GPa)

Uniaxialcompressivestrength(MPa)

Softeningcoefficient

A Siltstone 2570 4746 582 025 589 2278 048B Fine sandstone 2516 3185 376 013 523 1720 054

C Medium-grainedsandstone 2461 3014 449 018 523 2200 073

D Mudstone 2465 2413 163 011 310 mdash mdashE Mudstone 2575 2305 222 010 430 645 028

(a) Shed leg twisted (b) Floor heaved seriously

(c) Roof fractured (d) Connection failure

Figure 4 Deformation and failure of the roadway after repairing

minus700

minus700

minus560

minus580

minus600

minus620

minus640

minus660

minus600

minus680

minus660

minus580

minus560

minus680

minus660

minus660

minus640

minus620 72458060176

12

4

3

1307 working face

minus650 main roadway in the south wingMonitoring sections123 4 5

15∘

9∘

N1203∘ 51

998400 11998400998400 E100m trial raodway

70∘H

=0sim25m

70∘H = 0 sim

18m

CF6ang

DF54 ang

Figure 5 The locations of boreholes 1sim4

Shock and Vibration 5

4h 12h

24h 2d

Figure 6 Water-induced weakening process of mudstone

the surrounding rock The critical strength of the unstablecreep deformation of different surrounding rock strata is 12sim20MPa which is easily exceeded by the surrounding rockstress because of roadway excavation This explains why thesurrounding rock has large nonlinear flow deformations afterroadway excavation

322 Tectonic Stress Field Based on the tectonic stress testresults for the Yangcheng CoalMine [28] themajor principalstress in the in situ stress field is the horizontal stressThe azimuth angle of the maximum principal horizontalstress is 1123∘ The maximum principal horizontal stressis 2781MPa or 159 times greater than the vertical stressand 192 times greater than the minimum principal hori-zontal stress (1447MPa) The angle between the axis of themain roadway and maximum principal horizontal stress is877∘ The influence of the horizontal stress on the mainroadway during excavation can lead to severe failure of theroadway

33 Broken-Rock Zone and Failure Characteristics Thebroken-rock zone and failure characteristics were detected

by a borehole TV in several typical sections of the main softrock roadway (Figure 8) The field borehole TV detectiondiscovered that the rock surrounding the main roadway canbe divided into intact crack and fracture zones according tothe degree of failure [29] as shown in Figure 9 An intact zoneis defined as a region in which no fissures are observed alonga continuous distance of 30 cm of the borehole A crack zoneis defined as a region that contains 1-2 sets of fissures alonga continuous distance of 30 cm of the borehole A fracturezone is a region that contains three ormore fissures or evidentfracture along a continuous distance of 30 cm of the borehole

The surrounding rock failure of the main air returnroadway was analyzed based on these definitions of zonesGenerally speaking the surrounding rock is seriously dis-torted with a large broken-rock zone (approximately 2sim3mand even reaching 5m in some places) and discontinuousasymmetrical failure Many crack zones and fracture zonesare observed within a 3m range of the surrounding rockWhen the borehole depth exceeds 3m the crack zone andintact zone occur alternately As the borehole goes deeper thelength of the intact zone gradually increasesThe depth of thesurrounding rock failure is very large and the crack zone stillcan be detected at a depth of 8ndash10m

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

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Shock and Vibration

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DistributedSensor Networks

International Journal of

4 Shock and Vibration

Table 2 Physical and mechanical parameters of surrounding rocks

Serialnumber Lithology

Natural specimens Saturated specimens

Bulkdensity(KNsdotm3)

Uniaxialcompressivestrength(MPa)

Tensilestrength(MPa)

Poissonrsquosratio

Elasticmodulus(GPa)

Uniaxialcompressivestrength(MPa)

Softeningcoefficient

A Siltstone 2570 4746 582 025 589 2278 048B Fine sandstone 2516 3185 376 013 523 1720 054

C Medium-grainedsandstone 2461 3014 449 018 523 2200 073

D Mudstone 2465 2413 163 011 310 mdash mdashE Mudstone 2575 2305 222 010 430 645 028

(a) Shed leg twisted (b) Floor heaved seriously

(c) Roof fractured (d) Connection failure

Figure 4 Deformation and failure of the roadway after repairing

minus700

minus700

minus560

minus580

minus600

minus620

minus640

minus660

minus600

minus680

minus660

minus580

minus560

minus680

minus660

minus660

minus640

minus620 72458060176

12

4

3

1307 working face

minus650 main roadway in the south wingMonitoring sections123 4 5

15∘

9∘

N1203∘ 51

998400 11998400998400 E100m trial raodway

70∘H

=0sim25m

70∘H = 0 sim

18m

CF6ang

DF54 ang

Figure 5 The locations of boreholes 1sim4

Shock and Vibration 5

4h 12h

24h 2d

Figure 6 Water-induced weakening process of mudstone

the surrounding rock The critical strength of the unstablecreep deformation of different surrounding rock strata is 12sim20MPa which is easily exceeded by the surrounding rockstress because of roadway excavation This explains why thesurrounding rock has large nonlinear flow deformations afterroadway excavation

322 Tectonic Stress Field Based on the tectonic stress testresults for the Yangcheng CoalMine [28] themajor principalstress in the in situ stress field is the horizontal stressThe azimuth angle of the maximum principal horizontalstress is 1123∘ The maximum principal horizontal stressis 2781MPa or 159 times greater than the vertical stressand 192 times greater than the minimum principal hori-zontal stress (1447MPa) The angle between the axis of themain roadway and maximum principal horizontal stress is877∘ The influence of the horizontal stress on the mainroadway during excavation can lead to severe failure of theroadway

33 Broken-Rock Zone and Failure Characteristics Thebroken-rock zone and failure characteristics were detected

by a borehole TV in several typical sections of the main softrock roadway (Figure 8) The field borehole TV detectiondiscovered that the rock surrounding the main roadway canbe divided into intact crack and fracture zones according tothe degree of failure [29] as shown in Figure 9 An intact zoneis defined as a region in which no fissures are observed alonga continuous distance of 30 cm of the borehole A crack zoneis defined as a region that contains 1-2 sets of fissures alonga continuous distance of 30 cm of the borehole A fracturezone is a region that contains three ormore fissures or evidentfracture along a continuous distance of 30 cm of the borehole

The surrounding rock failure of the main air returnroadway was analyzed based on these definitions of zonesGenerally speaking the surrounding rock is seriously dis-torted with a large broken-rock zone (approximately 2sim3mand even reaching 5m in some places) and discontinuousasymmetrical failure Many crack zones and fracture zonesare observed within a 3m range of the surrounding rockWhen the borehole depth exceeds 3m the crack zone andintact zone occur alternately As the borehole goes deeper thelength of the intact zone gradually increasesThe depth of thesurrounding rock failure is very large and the crack zone stillcan be detected at a depth of 8ndash10m

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

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Submit your manuscripts athttpwwwhindawicom

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DistributedSensor Networks

International Journal of

Shock and Vibration 5

4h 12h

24h 2d

Figure 6 Water-induced weakening process of mudstone

the surrounding rock The critical strength of the unstablecreep deformation of different surrounding rock strata is 12sim20MPa which is easily exceeded by the surrounding rockstress because of roadway excavation This explains why thesurrounding rock has large nonlinear flow deformations afterroadway excavation

322 Tectonic Stress Field Based on the tectonic stress testresults for the Yangcheng CoalMine [28] themajor principalstress in the in situ stress field is the horizontal stressThe azimuth angle of the maximum principal horizontalstress is 1123∘ The maximum principal horizontal stressis 2781MPa or 159 times greater than the vertical stressand 192 times greater than the minimum principal hori-zontal stress (1447MPa) The angle between the axis of themain roadway and maximum principal horizontal stress is877∘ The influence of the horizontal stress on the mainroadway during excavation can lead to severe failure of theroadway

33 Broken-Rock Zone and Failure Characteristics Thebroken-rock zone and failure characteristics were detected

by a borehole TV in several typical sections of the main softrock roadway (Figure 8) The field borehole TV detectiondiscovered that the rock surrounding the main roadway canbe divided into intact crack and fracture zones according tothe degree of failure [29] as shown in Figure 9 An intact zoneis defined as a region in which no fissures are observed alonga continuous distance of 30 cm of the borehole A crack zoneis defined as a region that contains 1-2 sets of fissures alonga continuous distance of 30 cm of the borehole A fracturezone is a region that contains three ormore fissures or evidentfracture along a continuous distance of 30 cm of the borehole

The surrounding rock failure of the main air returnroadway was analyzed based on these definitions of zonesGenerally speaking the surrounding rock is seriously dis-torted with a large broken-rock zone (approximately 2sim3mand even reaching 5m in some places) and discontinuousasymmetrical failure Many crack zones and fracture zonesare observed within a 3m range of the surrounding rockWhen the borehole depth exceeds 3m the crack zone andintact zone occur alternately As the borehole goes deeper thelength of the intact zone gradually increasesThe depth of thesurrounding rock failure is very large and the crack zone stillcan be detected at a depth of 8ndash10m

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

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Navigation and Observation

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DistributedSensor Networks

International Journal of

6 Shock and Vibration

00

05

10

15

20

25

30

35

0 6 12 18 24 30 36 42 48Time (h)

Stra

in (m

m)

0

2

4

6

8

10

12

Stre

ss (M

Pa)

StrainStress

(a) Rock sample of mudstone

Stra

in (m

m)

0 24 48 72 96 120 14400

05

10

15

20

25

30

35

StrainStress

Time (h)

0

2

4

6

8

10

12

14

16

18

Stre

ss (M

Pa)

(b) Rock sample of medium-grained sandstone

Stra

in (m

m)

StrainStress

0 24 48 72 96 120 14400

05

10

15

20

Time (h)

02468101214161820

Stre

ss (M

Pa)

(c) Rock sample of fine sandstone

Figure 7 Uniaxial creep strain and creep stress curves

4 Failure Mechanism of the MainSoft Rock Roadway

Experimental and field tests showed that the internal causesfor the instability of the roadway were the weak surroundingrock and high tectonic stress The unreasonable supportdesign was the external cause

Low strength and wide development of joint fissuresof the surrounding rock significantly decrease the bearingcapacity of the surrounding rock The horizontal stress (159times greater than the vertical stress) which is the majorprincipal stress in the in situ stress field is almost perpen-dicular to the roadway direction The high horizontal stresscaused a major concentration stress in the roof and floor ofthe roadway Deformation and instability first occurred in theroof and floor

After failure of the roadway roof and floor the rockmasses against the two roadway ribs had large stress

concentrations in a biaxial stress state The concentratedstress causes the abundant primary joint fissures to expandand interconnect with each other to form an unstable sur-rounding rock structure with a fracture zone and crack zoneoccurring alternately Because the surrounding rock in thefracture zone loses bearing capacity completely the abutmentpressure of the rock surrounding the roadwaymigrates to thecrack zone and deeper intact zone which will turn the crackzone into a fracture zone and the intact zone into a crack zoneuntil the surrounding rock stabilizes

The borehole TV showed that the broken-rock zone ofthe roadway was approximately 2-3m which exceeded theeffective anchorage length of the bolts The maximum failuredepth of the crack zone in the roadway extended 8ndash10mwhich was wider than the length of the cables So the boltsand cables were in fact useless and the U-shaped steel shedswere unable to support the deformations of the large quantityof broken surrounding rock

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

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Active and Passive Electronic Components

Control Scienceand Engineering

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RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

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Electrical and Computer Engineering

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Advances inOptoElectronics

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 7

Fracture of 036m deep Fissures of 115m deep Fracture of 174m deep Fissure of 257m deep

Fissure of 412m deep Fissures of 804m deep Fissure of 882m deep Fissure of 966m deep

FractureFracture

Open fissure

Fissure

Circumferentialfissure Intersectant fissures

Radial fissureRadial fissure

Fissure

(a) Drilling in the roof strata

Fracture of 03m deep Fracture of 119m deep Open fissure of 173m deep Fissures of 332m deep

Fracture of 347m deep Fissure and fracture of 473m deep Fracture of 776m deep Fissure of 847m deep

Circumferentialfissure

Fracture

Open fissure

Fracture

Open fissure

FissureOpen fissureFractureFracture

Fracture

(b) Drilling in the ribs strata

Figure 8 Fracture patterns of surrounding rocks from borehole TV observation

5 Support Design

Although the supporting capacity of the previous supportwas very high the main roadway deformed seriously Theold support design is unscientific and lacking specificityA new and better support design is needed to control theroadway deformations and instability Based on the results ofexperiments and field tests the new design should considerthe following

(1) Rapid support installation after excavation [1] thesurrounding rock of the deep high-stress road-way may deform immediately after roadway excava-tion because of the stress concentration Therefore

installing the bolts and cables at an early stage isessential and can avoid premature yield failure of thesurrounding rock and allow the support to work withthe intact rock

(2) Long cable field tests showed that the depth of thesurrounding rock failure was very large and manycracks still can be detected 8m deep or deeper Thecable length of the old support is 64mwhich ismuchless than the depth of the surrounding rock failureso it cannot control the stability of the surroundingrock The new long cable should terminate inside therelatively intact rock So the length of new long cables

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

8 Shock and Vibration

(a) Intact zone (b) Crack zone

(c) Fracture zone

Figure 9 Three typical zones around the surrounding rock

should be greater than the depth of the surroundingrock failure

(3) Grouting reinforcement field test results showed thatthe surrounding rock was weak because of widedevelopment of joint fissures and a large broken-rock zone these conditions were the main causes ofthe roadway instability The best way to improve thisis to use a grouting reinforcement support becausethis can rebuild loose and broken surrounding rockinto a solid rock Another benefit is that groutingcan seal fissures of the surrounding rock and preventinfiltration of water and air avoiding the softeningeffect of water and air on the rocks and increasingbearing capacity

(4) High pretension high pretension plays an importantrole in roadway support because it can significantlyenhance the strength of the anchorage body

Based on these considerations a new support design waspresentedThe specific layout of the bolts cables and so forthis shown in Figure 10 The new support combines boltingshotcreting with wire mesh anchor cabling and groutingMoreover a deep and superficial coupling grouting supportis achieved with a grouting pipe and grouting cable as seen inFigure 10The grouting pipe rebuilds the broken surroundingrocks by forming an integral load-bearing ring whereasthe grouting cable seals the deep fracture and stabilizesthe superficial load-bearing ring The floor is supported by

an overbreak and bolt-grouting backfill technology that canincrease the integrity and bending resistance of the floorSpecific support parameters in the new support design areintroduced as follows

(1) Bolt parameters there are twenty-five bolts in theroadway cross section including eight bolts in theroof twelve bolts in the ribs and five bolts in thefloorThe bolts have a diameter of 22mm and a lengthof 25m The spacing between the bolts in the roofand ribs along the roadway axis is 07m The spacingbetween the bolts in the roof and ribs along theroadway radial is 07mThe spacing between the boltsin the floor is 09m Metal meshes are applied beforethe anchor rod reinforcement Fifty-millimeter thickshotcrete will be constructed (primary shotcrete) assoon as possible after the bolting supportThe anchor-age length of each bolt must be greater than 06m Allbolts should be pretensioned with a pretension loadof 70 kN The bolts are made of levorotary rebar steelwith a tensile strength of 500MPa

(2) Metal mesh parameters metal mesh is welded to steelbar that has a diameter of 6mm The metal mesh hasa length of 20m and a width of 10m The grid ofthe metal mesh has a lengthwidth ratio of 01 Themetal mesh is installed to the whole roadway sectionand two adjacent metal meshes are connected by ironwire

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 9

grouting cable

R2400

4200

bottom anglegrouting cable

4800

800 Floor backfill

900

Shotcretelayer

150

150

700

1400

Φ22 times 10000mm

Φ22 times 6000mm

Φ22 times 2500mm bolt

(a) Anchor robs and cables support design

Shotcretelayer

R2400

grouting lines

5000

4800

1800 1800

150

150

1800

Φ26 times 2500mm

(b) Grouting lines support design

Figure 10 New supporting design of the roadway

8 9 10 11

1 2 3 4 5 6 7

(1) Anchor head (2) Steel strand (3) Grouting core tube (4 7) Flow hole of slurry(5) Metal sleeve

(6) Void (8) Shallow closed area (9) High pressure grouting section (10) Low pressure grouting section (11) Anchoring section

Figure 11 Structure of grouting cable

(3) Grouting pipe parameters there are ten groutingpipes in a roadway cross section including five inthe roof two in the ribs and three in the floorThe grouting pipes have a diameter of 26mm and alength of 25m The intervals between the groutingpipes along the roadway axis and radial are both18m Grouting lines are paved immediately after theprimary shotcrete support

(4) Grouting cable parameters based on the surround-ing rock deformation characteristics of the roadwaymeasured from experiments and field tests a newgrouting cable is designed as seen in Figure 11 Thenew grouting cable has many advantages such as asmall grouting resistance large flow high efficiencyand wide application range Gradual grouting fromthe deep surrounding rock to the superficial sur-rounding rock can be achieved with high and lowpressure grouting sections of the new grouting cableThere are eleven grouting cables in a roadway cross

section including five in the roof four in the ribsand two in the bottom angle The grouting cableshave a diameter of 22mm and a length of 100min the roof and ribs and 60m in the bottom angleThe intervals between the grouting cables in the roofand ribs along the roadway and radial axes are both14m The spacing between the grouting cables inthe bottom angle along the roadway axis is 14mThe anchorage length of each grouting cable mustbe larger than 15m All grouting cables should bepretensioned with a pretension load of 200 kN Thegrouting cables are made of steel strand with a tensilestrength of 1860MPa Grouting cables are installedafter the grouting pipes and secondary shotcrete withthe thickness of 100mm is applied as soon as thegrouting cable pavement is finished

(5) Grout parameters the grout is a single liquid pre-pared from Po425 ordinary silicate cement with awatercement ratio of 1 2The final grouting pressureof the grouting-anchor cable is 3sim4MPa and the finalgrouting pressure of the grouting lines is 15sim2MPa[17] The grouting is implemented within 15sim18 daysafter roadway excavation so the grouting is mosteffective [30]

(6) Concrete parameters the strength of the sprayedconcrete is C20 and the strength of the concrete forfloor backfilling is C40 which includes an addedwaterproofing agent Normal concrete easily breakswhen the surrounding rock experiences a large defor-mation Hence steel fibers are added in the concreteto increase flexibility and deformability of the con-crete layers Furthermore the metal meshes can alsoincrease the tensile strength of the concrete layers

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

10 Shock and Vibration

A

B

D

E

C

Horizontalreference line

Verticalmeasuring line

800

2400

4800

Figure 12 Monitoring sites for the deformation of the roadway

Backfilling the extra excavation space of the floorwithconcrete is conducted last

Compared to the old support design the new supportdesign can bond the support with the surrounding rock ofthe roadway and fully utilize the self-supporting capability ofthe surrounding rock

6 On-Site Experiments and Monitoring

Field industrial experiments andmonitoring were performedin theminus650main roadway in the southwing of the YangchengCoal Mine to test the effectiveness of the new support designand compare it with the old support design One 100msegment of roadway was chosen as a trial of the new supportdesign and the other roadways were supported with theold support design shown in Figure 3 The deformation ofthe roadway was measured by extensometers with 02mmaccuracy A total of five roadway cross sections were moni-tored at an interval of 30m between two sectionsMonitoringsections 1 2 and 3 were in the roadway with the new supportdesign and monitoring sections 4 and 5 were in the roadwaywith the old design The locations of the monitoring sectionsare shown in Figure 5

The measuring method of each cross section is shown inFigure 12 In Figure 12 B and E are two vertical data marksfixed in the roof and floor of the roadway respectively and Cand D are two horizontal data marks fixed in the ribs CD isthe horizontal reference line and BE is the vertical measuringline A is the node of CD and BE A decreasing length of CDmeans shrinkage of the two ribs a decreasing length of BAmeans settlement of the roof and a decreasing length of AEmeans heaving of the floor

Monitoring of all five roadway cross sections started assoon as possible after all of the supports were installedMonitoring for sections 1 to 3 lasted for 90 days Deformationand the deformation rate were both very large in the roadwaywith the old support design therefore to ensure safety of theworkers sections 4 and 5 were monitored for only 70 days

The monitoring results are shown in Figures 13 14 15and 16 The monitoring results of sections 1 to 3 showedthat there was an obvious increase in the deformation duringthe first 12 days after supporting the roadway Howeverafter approximately 12 days the deformation rates started todecrease and the deformations appeared to be stable afterapproximately 30 to 60 days For the comparable sections 4and 5with the old support design the deformation continuedto increase over thewholemonitoring period and no obviousdecline in the deformation rates was observed during themonitoring period

After monitoring the maximum monitored ribs con-vergence roof settlement and floor heave in the roadwaywith the new support design were 56mm (section 3) 44mm(section 1) and 44mm (section 3) respectively In sections 4and 5 with the old support design these results were 601mm(section 4) 2956mm (section 4) and 5172mm (section 5)respectively It is clear that the roadway deformation withthe new support design is much smaller than that with theold design A similar conclusion is drawn by comparing thedeformation rates of the ribs convergence roof settlementand floor heave in the roadway with the new support designand the old design The highest deformation rates of the tworibs roof and floor of the roadway with the new supportdesign were 3mmd 4mmd and 27mmd respectivelycompared to 17mmd 10mmd and 14mmd in the roadwaywith the old design

In general compared with the old support design thenew support design can reduce the roadway deformation byat least 85ndash90 During the monitoring period the roadwayroof ribs and floor with the new support design were intactand no obvious failure was visible In contrast the roadwaywith the old design experienced large deformations andsevere failure This indicates that the new support designcan effectively control the deformation of the roadway andmaintain stability of the roadwayThe effectiveness of the newsupport design can be visually observed in Figure 17

7 Conclusions

A case study of the failure mechanisms and support technol-ogy for deep composite soft rock roadways was performedon the Yangcheng Coal Mine in Shandong Province ChinaThe buried depth of the main roadway was approximately700m and the surrounding rock of the roadway was weakand broken Bolts combined with cables metal mesh andeven U-shaped steel sheds were used as permanent supportsto control the surrounding rock However the main roadwaystill suffered large deformations and seriously unstable fail-ures

Both a field survey and an experimental study showedthat the surrounding rock of the roadway was an HJScomplex soft rock characterized by poor rock quality widedevelopment of joint fissures and an unstable creep propertyThe broken-rock zone of the roadway surrounding rock waslarge and the maximum depth of the fissures exceeded 8mThe tectonic stress field test showed that the major horizontalstress was approximately 159 times greater than the vertical

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 11

0

10

20

30

40

50D

efor

mat

ion

(mm

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 1

Def

orm

atio

n (m

m)

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

Date (d)

(b) Roadway cross section 2

Shrinkage of the two ribs Settlement of roofFloor heave

0 12 24 36 48 60 72 840

10

20

30

40

50

60

Date (d)

Def

orm

atio

n (m

m)

(c) Roadway cross section 3

Figure 13 The cumulative deformation of the roadway with the new support design

stress The angle between the axis of the main roadway andthe major horizontal stress was 877∘ The weak surroundingrock and high tectonic stress were the main internal causesof roadway instabilities and the unreasonable support designwas the external cause

Based on the results of experiments field tests andextensive analysis a new support designwas proposed whichincluded a reasonable support arrangement long cablesgrouting reinforcement high pretensioning of bolts andcables and overbreak and bolt-grouting backfill for the floorsupport Furthermore a new grouting cable was inventedspecifically to control the roadway deformation and failure

An on-site industrial experiment of the new supportdesign was performed in a roadway section approximately100m long The monitoring results confirmed that the newsupport design was much more effective than the old designThe new support design reduced the deformations of theroadway by at least 85ndash90 compared to that of the previousroadway This case study indicated that a deep composite

soft rock roadway similar to the minus650 main roadway in thesouth wing of the Yangcheng Coal Mine could be steadilycontrolled with an elaborate field investigation scientificanalysis and reasonable support design The success ofthis case provides significant guidance for similar roadwayconstruction engineering projects which will be welcomedby other coal mines

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This work was supported by the National Basic ResearchProgramof China (2014CB046905) theNational Natural Sci-ence Foundation of China (51274191 51404245 51374140 and

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

12 Shock and Vibration

0002040608101214161820

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

(a) Roadway cross section 1

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

000204060810121416182022

(b) Roadway cross section 2

Def

orm

atio

n ra

te (m

md

)

0 12 24 36 48 60 72 84Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

00

05

10

15

20

25

30

35

40

45

(c) Roadway cross section 3

Figure 14 The rate of deformation of the roadway with the new support design

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(a) Roadway cross section 4

0

100

200

300

400

500

600

Def

orm

atio

n (m

m)

0 12 24 36 48 60 72Date (d)

Shrinkage of the two ribs Settlement of roofFloor heave

(b) Roadway cross section 5

Figure 15 The cumulative deformation of the roadway with the old support design

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

Shock and Vibration 13

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

02468

1012141618

Def

orm

atio

n ra

te (m

md

)

(a) Roadway cross section 4

02468

10121416

0 12 24 36 48 60 72Date (d)

Shrinkage rate of the two ribsSettlement rate of roofFloor heave rate

Def

orm

atio

n ra

te (m

md

)

(b) Roadway cross section 5

Figure 16 The rate of deformation of the roadway with the old support design

Figure 17 The roadway with new supporting design

51204159) and Doctoral Fund of Ministry of Education ofChina (20130095110018) The authors thank the anonymousreferees for their careful reading of this paper and valuablesuggestions

References

[1] B Shen ldquoCoal mine roadway stability in soft rock a case studyrdquoRock Mechanics and Rock Engineering vol 47 no 6 pp 2225ndash2238 2013

[2] M C He H H Jing and X M Sun Soft Rock EngineeringMechanics Science Press Beijing China 2002

[3] Y L Lu L G Wang F Yang Y Li and H Chen ldquoPost-peakstrain softening mechanical properties of weak rockrdquo ChineseJournal of Rock Mechanics and Engineering vol 29 no 3 pp640ndash648 2010

[4] M C He G F Li J Wang and J Cai ldquoStudy on supportingdesign for large area serious roof caving of deep soft rock road-way in Xingrsquoan coal minerdquo Chinese Journal of Rock Mechanicsand Engineering vol 26 no 5 pp 959ndash964 2007

[5] Y P Wu C Wang M P Li Y F Zeng and C H HuangldquoMechanism of roof-floor shearing deformation and breakagein coalmine of soft rock roadwayrdquo Journal of Xirsquoan University ofScience and Technology vol 27 no 4 pp 539ndash543 2007

[6] C Li Z LWang and T Liu ldquoPrinciple and practice of couplingsupport of double yielding shell of soft rock roadway under high

stressrdquo International Journal of Mining Science and Technologyvol 24 no 4 pp 513ndash518 2014

[7] B Meng H-W Jing K-F Chen H-J Su S-Q Yang and Y-H Li ldquoShear and slip failure mechanism and control of tunnelswith weak surrounding rockrdquo Chinese Journal of GeotechnicalEngineering vol 34 no 12 pp 2255ndash2262 2012

[8] H Salari-Rad M Mohitazar and M R Dizadji ldquoDistinctelement simulation of ultimate bearing capacity in jointed rockfoundationsrdquo Arabian Journal of Geosciences vol 6 no 11 pp4427ndash4434 2013

[9] R Seedsman ldquoThe stress and failure paths followed by coalmine roofs during longwall extraction and implications to tail-gate supportrdquo inProceedings of the 20th International Conferenceon Ground Control in Mining pp 42ndash49 Morgantown WVaUSA 2001

[10] L Yuan J-H Xue Q-S Liu and B Liu ldquoSurrounding rockstability control theory and support technique in deep rockroadway for coal minerdquo Journal of the China Coal Society vol36 no 4 pp 535ndash543 2011

[11] L Wu C Cui N Geng and J Wang ldquoRemote sensingrock mechanics (RSRM) and associated experimental studiesrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 37 no 6 pp 879ndash888 2000

[12] W P Huang Y F Gao and J Wang ldquoDeep rock tunnelrsquos longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[13] H P Kang J Lin and Y Z Wu ldquoDevelopment of high preten-sioned and intensive supporting system and its application incoal mine roadwaysrdquo Procedia Earth and Planetary Science vol1 pp 479ndash485 2009

[14] Y-Y Jiao L Song X-Z Wang and A Coffi Adoko ldquoImprove-ment of the U-shaped steel sets for supporting the roadways inloose thick coal seamrdquo International Journal of Rock Mechanicsand Mining Sciences vol 60 pp 19ndash25 2013

[15] Y L Lu L G Wang and B Zhang ldquoAn experimental study of ayielding support for roadways constructed in deep broken softrock under high stressrdquoMining Science and Technology vol 21no 6 pp 839ndash844 2011

[16] C Wang Y Wang and S Lu ldquoDeformational behaviourof roadways in soft rocks in underground coal mines and

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

14 Shock and Vibration

principles for stability controlrdquo International Journal of RockMechanics andMining Sciences vol 37 no 6 pp 937ndash946 2000

[17] L-G Wang M-Y Li and X-Z Wang ldquoStudy of mechanismsand technology for bolting and grouting in special soft rockroadways under high stressrdquo Chinese Journal of Rock Mechanicsand Engineering vol 24 no 16 pp 2889ndash2893 2005

[18] L-G Wang H-L Li and J Zhang ldquoNumerical simulationof creep characteristics of soft roadway with bolt-groutingsupportrdquo Journal of Central South University of Technology(English Edition) vol 15 no 1 supplement pp 391ndash396 2008

[19] H Lisa GGunnar F Asa andN Tommy ldquoA statistical groutingdecision method based on water pressure tests for the tunnelconstruction stagemdasha case studyrdquo Tunnelling and UndergroundSpace Technology vol 33 pp 54ndash62 2013

[20] S Nadimi and K Shahriar ldquoExperimental creep tests andprediction of long-term creep behavior of grouting materialrdquoArabian Journal of Geosciences vol 7 no 8 pp 3251ndash3257 2014

[21] W P Huang Y F Gao and J Wang ldquoDeep rock tunnels longlarge deformation mechanism and control technology underdisturbance effectsrdquo Journal of China Coal Society vol 39 no5 pp 822ndash828 2014

[22] X M Sun D Wang C Wang X Liu B Zhang and Z LiuldquoTensile properties and application of constant resistance andlarge deformation boltsrdquoChinese Journal of RockMechanics andEngineering vol 33 no 9 pp 1765ndash1771 2014

[23] S R Torabi H Shirazi H Hajali andMMonjezi ldquoStudy of theinfluence of geotechnical parameters on the TBM performancein Tehran-Shomal highway project using ANN and SPSSrdquoArabian Journal of Geosciences vol 6 no 4 pp 1215ndash1227 2013

[24] W J Wang G Peng and J Huang ldquoResearch on high-strengthcoupling support technology of high stress extremely soft rockroadwayrdquo Journal of the China Coal Society vol 36 no 2 pp223ndash228 2011

[25] X Huang Q-S Liu and Z Qiao ldquoResearch on large deforma-tion mechanism and control method of deep soft roadway inZhuji coal minerdquo Rock and Soil Mechanics vol 33 no 3 pp828ndash834 2012

[26] N M Esfahani and O Asghari ldquoFault detection in 3D bysequential Gaussian simulation of Rock Quality Designation(RQD)rdquo Arabian Journal of Geosciences vol 6 no 10 pp 3737ndash3747 2013

[27] M R Shen and J F Chen Rock Mechanics Tongji UniversityPress Shanghai China 2006

[28] Q S Li F L Bo X Y Ding et al ldquoDeformation characteristicsof soft rock roadway in deep mines and supporting controltechnologyrdquo Journal of Shandong University of Science andTechnology (Natural Science) vol 29 no 4 pp 8ndash14 2010

[29] S C Li H P Wang Q H Qian et al ldquoIn-situ monitoringresearch on zonal disintegration of surrounding rock mass indeep mine roadwaysrdquo Chinese Journal of Rock Mechanics andEngineering vol 27 no 8 pp 1545ndash1553 2008

[30] Y-L Lu L-G Wang B Zhang and Y-J Li ldquoOptimizationof bolt-grouting time for soft rock roadwayrdquo Rock and SoilMechanics vol 33 no 5 pp 1395ndash1401 2012

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Active and Passive Electronic Components

Control Scienceand Engineering

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Shock and Vibration

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Civil EngineeringAdvances in

Acoustics and VibrationAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawi Publishing Corporation httpwwwhindawicom

Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chemical EngineeringInternational Journal of Antennas and

Propagation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Navigation and Observation

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

DistributedSensor Networks

International Journal of