is.10270.1982
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Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.
!"#$%&# '(%)
“ !"# $ %& #' (")* &" +#,-. ”Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“ /0 )"1 &2 324 #' 5 *)6 ” Jawaharlal Nehru
“Step Out From the Old to the New”
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“The Right to Information, The Right to Live”
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“Knowledge is such a treasure which cannot be stolen”
IS 10270 (1982): Guidelines for design and construction of
prestressed rock anchors [CED 43: Soil and Foundation
Engineering]
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(Reaffirmed 2003)
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IS :10270 1982
ndian St andard
GUIDELINES FOR
DESIGN AND CONSTRUCTION OFPRESTRESSED ROCK ANCHORS
Foundation Eng neering Sectional Committee, BDC 43
Chairman Representing
PROF DINESH MORAN Centl;aborft ding Research
Members
Da R. K. BHANDAUI Central Building ResearchRoorkee
SH~I DEVENDRA SHARMA (Alternate)
Institute ( CSIR ),
Institute (CSIR ),
CHIEF ENOINEER Calcutta Port Trust, CalcuttaSHRI S. GUHA Alternafe )
SHRI M. G. DANDA~ATE The Concrete Association of India, BombaySHRI N. C. DTJ ~C+A> Alternate )
In personal capacity (5, Hungerford Court, 121,Hungrrford Street, Calcutta )
SHRI A. G. DASTIDAR
SHRI V. C. DESHPANDEDIRECTOR CSMRS )
The Pressure Pil ing Co (I) Pvt Ltd, BombayCentral Soil & Material Research Station, New
DEPUTY DIRECTORSH~I A. H. DIVANJ I
SHRI A. N. J ANQLESHRI A. GHOSALSHRI R. K. DAS GUPTA
DelhiCSMRS ) ( Alternate )
AsiaBpmyadyations and Construction Pvt Ltd,
Alternate )Stup Consultants Limited, BombaySimplex Concrete Piles ( India ) Private L imited,
CalcuttaSHRI H. GUHA BISWAS ( Alternate )
DR J AODISH NARAIN Indian Geotechnical Society, New Delhi
PROF SWAMI SARAN ( Alternate)SHRI G. S. J AIN G. S. J ain & Associates, Roorkee
SHRI ASHOK KUMAR J AIN ( Alternate )
Soar N. J AQANNATH Steel Authority of India, BokaroSHRI A. K. MITRA (Alternate)
J OINT DIRECTOR ( DESIGNS ) National Buildings Organization, New DelhiSHRI SUNIL BERY ( Alternate )
( Continued on page 2 )
Q Coplridhl1982
INDIAN STANDARDS INSTITUTION
This publication is protected under the Indian CoBright Act (XIV of 1957) and
reproduction in whole or in part by any means except with written permission ofthe
publisher shall be deemed to be an i&ingement of copyright under the aaid Act.
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IS :10270 1982
( ontinued from page 1 )
Members
J O~IN:RE~TOR RESEARCH (GE)-I ,
J OINT DIRECTOR RESEARCH
( B&S ), RDSO ( Alternate )DR R. K. KATTISHRI S. R. KULXAR~I
Srrar S. ROY ( Alternate )
SHRI 0. P. MAL I IOTRA
SHRI A. P. MATHCRSHRI V. B. MATHUXSHRI T. K . D. MUNSI
SHRI M. IY ENQAR ( Alternate )SHRI B. K. PANTHAKY
SHRI V. M. MADQE ( Afternate )
SHRI M. R. PUNJ ASHRI S. MUKRERJ EE ( Alternate 1
Representing
Ministry of Railways
Indian Institute of Technology, BombayM. N. Dastur & Co Pvt Ltd, Calcutta
Public WorksAdministration
Department, Chandigarh
Central Warehousing Corporation, New DelhiMachenzies L imited, BombayEngineers India Limited, New Delhi
The Hindustan Construction Co Ltd, Bombay
Cemindia Co Ltd, Bombay
&RI N. E. V. RAGHVAN
PROF GOPAI, RANJ ANSHRI T. N. SUBBA RAO
The Braithwaite Burn & J essop ConstructionCompany Limited, Calcutta
University of Roorkee, RoorkeeGammon India Limited, Bombay
SHRI S. A. REDDI ( Alternate)
DR V. V. S. RAO Nagadi Consultants Private Ltd, New Delhi
SHRI ARJ UN RIJ HSIN~RANI Cement Corporation of India, New Delhi
SHRI 0. S. SRIVASTAVA ( Alternate )
Dn A. SARGUNAN College of Engineering, Guindy, Madras
SHRI S. BOM~~INATHAN Alternate )
SHRI K . R. SAXENA Engineering Research Laboratories, Governmentof Andhra Pradesh, Hyderabad
BRIQ OMBIR SIN~XI Engineer-in-Chief’s Branch, Army Headquarters
LT-COL K. P. ANAXD ( Alternate )
SHRI N. SIVAG~RU Ministry of Shipping and Transport (RoadsWing ), New Delhi
SHRI K. B. SARKAR (Alternate)
SUPERINTEKDING E N Q I N E E R Central Public Works Department, New Delhi
( DESIGNS )
EXECUTIVE ENGINEER( DESIGNS ) V ( Alternate )
SHRI M.D. TAMBEKAR Bombay Port Trust, Bombay
DR A. VARADARAJ AN Indian Institute of Technology, New Delhi
DR R. KANI RAJ (Alternate )
SHRI G. RAMAN, Director General, IS1 ( Ex-o o Member)
Director (Civ Engg )
Secretary
SHRI K. M. MATHURDeputy Director ( Civ Engg ), IS1
( Continued on pge 13 )
L
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IS:10270 1982
Indian Standard
GUIDELINES FOR
DESIGN AND CONSTRUCTION OF
PRESTRESSED ROCK ANCHORS
0. FOREWORD
0.1 his Indian Standard was adopted by the Indian StandardsInstitution on 27 July 1982, after the draft finalized by the FoundationEngineering Sectional Committee had been approved by the CivilEngineering Division Council.
0.2 Ground anchors are used in civil engineering for the followingapplications:
a) To resist lateral thrust on retaining walls and in-situ diaphragmwalls,
b) For stabilizing of slopes and land slides,
c) To resist uplift on basements and other foundations,
d) To strengthen masonry and concrete dams, and
e) For testing of large diameter piles.
0.2.1 This standard is being prepared as a guideline for design andconstruction of prestressed rock anchors. The other types of anchors, suchas prestressed soil anchors or unstressed rock anchors are not covered inthis standard.
0.3 For the purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculatedexpressing the result of a test or analysis, shall be rounded off inaccordance with IS : 2-1960*. The number of significant places retainedin the rounded off value should be the same as that of the specified value
in this standard.
1. COPE
1.1 his standard deals with design and construction of permanent andtemporary prestressed rock anchors constructed by using high strengthprestressing steel ( wires and strands ).
*Rules for rounding off numerical values ( rcv5scd).
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IS : 10270 - 1982
2. TERMINOLOGY
2.0 For the purpose of this standard the following definitions shall apply(see Fig. 1 ).
2.1 Permanent Anchors - Any anchor required and constructed forservice life of the structure.
2.2 Temporary Anchors - Any anchor required and constructed forduration of construction period only.
2.3 Fixed Length - The length of the anchor which is grouted in, from
which the pullout capacity of anchor is achieved.
2.4 Free Length - The part of the anchor which is not bonded to the
surrounding area and is free to elongate.
2.5 Fixed Length Grout - Cement grout which is placed/injected in
the fixed length of the anchor that provided anchorage.
2.6 Free Length Grout - The grout surrounding the free length of theanchor. This secondary injection is provided surrounding the sheathing
in case of sheathed anchors. For unsheathed anchors, this grout isprovided after the stressing is completed and anchor is locked. The mainpurpose of this grout is to provide corrosion protection.
2.7 Consolidation Grouting -Grouting executed in the areasurrounding the hole prior to inserting cables either to waterproof the
hole or to strengthen the rock.
2.8 Design Load - Assigned load on anchor after allowance for all
losses.
2.9 Prestressing Steel - The element of the anchor which is allowedto elongate and is anchored at the bottom to develop necessaryprestressing force. This steel can be high tensile plain wires or standard
cables.
2.10 Sheathing - Enclosure to the prestressing steel provided forcorrosion protection.
2.11 Anchorage - The means by which prestressing force is transmittedto rock or structural element.
2.12 Bearing Plate-A plate used at the top end of the prestressedanchor to distribute anchor force to the structure.
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I S: 10270 - 1982
H? WIRES
71 YAMCHOR HEAo
BEARtNG P
; CONCRETE
i’i .b: ’
’ ‘.: 3. *
wwaL
TRUMPEi PIPE
--DRILL HOLE
OVER BURDEN
GROUT
1
I
52w4
3wY
SEAL
ROUT PIPF
ATE
FIG. 1 TYPICAL DETAILS OF PRESTRESSED OCK ANCHOR
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2.13 Allowable Bond Stress of Rock- Bond stress between the rockand the grout used in the design.. This normally assures a minimumsafety factor of 3.
2.14 Lugeon - Lugeon is defined as flow of water in litres/minutes/metre
length of the test section at a pressure of lMN/me ( 10 kgf/cm2 ) duringwater test.
2.15 Prestressing Force - The load to which the anchors are initiallystressed to cater for design load and allowance for the expected losses.
3. NECESSARY DATA
3.1 The following data are required for design and construction ofanchors:
a) Service life of anchor ( temporary or permanent );
b) Design load per anchor; and
c) Soil investigation for following factors:
i) Complete borehole log indicating types of soil and rockenco&tered with respect to depth,- T%e depth of penetrationinto rock with core drilling should be minimum 10 m( see IS : 1982-1979* ).
ii)
iii)
iv)
v)
Undrained shear strength and bulk density at different depths[see IS : 2720 (Part XI)-1971t].
Shear strength and unit weight of rock [see IS : 1121(Part IV)-1974: and IS : 1122-1974 -j.
Sulphate and chloride contents in so l as well as ground water[see IS : 2720 (Part XXII)-1977111.
Permeability of rock and fissures-pervious zones water tableand artisian head if any recorded on boreholes [ see IS : 5529( Part IT )-197311.
*Code of practice for subsurface investigation for foundations (Jirst revision).
tMethods of test for soils: Part XI Determination of the shear strength parametersof a specimen tested in uncosolidated undrained triaxial compression without themeasurement of pore water pressure.
.Methods of test for determination of strength properties of natural building stones:Part IV Shear strength (jirst revision).
gMethods of test for determination of true specific gravity of natural building stones(first revision .
jlMeth& of test for soils: Part XXII Determination of organic matter (first revision).
flCode of practice fori n si t u
permeability tests: Part II Tests in bedrock.
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Is : 10270 - 1982
4. MATERIALS
4.1 The cement shall be either ordinary Portland cement conformingto IS: 269-1976* or sulphate resistant cement conforming toIS : 6909-19737.
4.2 The prestressing steel shall conform to IS : 2090-1962:.
5. DESIGN CONSIDERATIONS
5.1 Prestressing Steel-The number of wires or strands are soprovided that initial prestressing force is at a level of 70 percent ofguaranteed ultimate tensile strength of the steel.
5.2 Fixed and Free Length of Anchors
5.2.1 The fixed length of the anchor is decided based on allowablebond stress between: (a) steel and grout, (b) the grout and the rock, and(cl shear strength of rock. The fixed length (bond length ) should beprovided considering the following aspects:
a) Co-relation between unconfined compressive strength of the rockand bond value ( see Fig. 2 ),
b) From the data available on typical rocks ( Table 1 ), and
c) Experience with similar type of rocks in adjacent areas.
NOTE-Considerable experience is required for assigning the bond value indesign of anchors. Several different aspects, such as, smoothness and roughness ofthe rock, shear strength of the rock, weathering, etc, are to be considered. To formthe basis to make a reasonable estimate of bond value, the above 3 aspects should beconsidered,
5.2.2 Free length of the anchor is decided based on the pulloutcriteria. In Fig. 3, method of checking the pullout capacity of anchorsis given. The minimum safety factor of 1.5 for permanent anchorsand 1.25 for temporary anchors is required against pullout. Minimumfree length of 5 m is considered desirable and if the pullout criterion
indicates free length should be provided.
6. METHOD OF CONSTRUCTION
6.1 Drilling Through Overburden - Drilling through overburden isnormally carried out by suitable equipment. For keeping the side stable,
*Specification for ordinary and low heat Portland cement ( third r evi sion .
+Specification for supcrsulphated cement.
Specification for high tensile steel bars used in prestressed concrete Jirstrevision).
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either temporary casing is provided or bentonite mud circulation is used.The size of the hole depends upon the capacity of the anchor. In case ofinclined bores use of casing tube shall be obligatory.
100 000
50 000
>
oo 5000 10000
ULTIMATE MEASURED BONO VALUE ,kN/, t
FIG. 2 TENTATIVE RELATION BETWEEN BOND AND UNCONFINED
COMPRESSIONSTRENGTH
6.2 Drilling Through Rock - Drilling through rock is carried out byusing either rotary method with water flush or using pneumaticpercussion method with air and/or water flush.
6.3 Water Proofing of the Hole - After drilling through rock a watertest is carried out and if water loss is found to be excessive the hole isgrouted (see IS : 6066-1971* ). The grout is then redrilled and watertest repeated and the whole procedure is repeated till satisfactory lugeon
*Recommendations ibr pressure grouting of rock foundations in river valley projects.
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IS : 10270 - 1 382
value is obtained. In case of temporary anchors repeative grouting andredrilling may not be done.
TABLE 1 ALLOWABLE ROCK GROUT BOND VALUES
( Clause 52.1 )
SL No. TYPE OF ROCK ALI~OWABLEBOND STREWS
1) 2) (3)
3
ii)
iii)
iv)
v)
vi)
vii)
viii)
Basalt
Khaondolite/Charnokite
Granite
Shale
Weathered sandstone/Quartzite
J ointed quartzitic
Grey chioritic schist
Sandstone/Quartzite
0’5N/mms to “IN/mm’
( 5kgf /cm” to 7kgf /cm2 )
0.3Njmms to .5N /m2( 3kgf /cm* to 5kgf /cm’)
0.5N/mms( 5kgf /cm’ )
0.3N/mms )( 3kgf /ems )
0.25N/mma( 2.5kgf /ems )
0*35N/mm* )
( 3.5kgf/cmz )
0.35N/mm* )
( 3*50kgf /mm* )
O*SN/mms( 3kgf /cm* )
6.4 Fabrication of Anchors - Anchors can be shop fabricated orfabricated on site depending upon the construction requirements.
6.4.1 Anchors shall be free of dirt, deterimental dust or any otherdeleterious substance. Anchors shall be handled and protected prior toinstallation to avoid corrosion or physical damage.
6.5 Lowering Anchors - Anchors are placed in accordance with typeof anchors. Suitable guide system and temporary fixing of the anchor isrequired to avoid movement of anchor during grouting. Grout tubes arechecked to ensure that they are free. Suitable spacers are also provided
when required to ensure that anchor assembly does not get entangled.
6.6 Fixed Length Grouting - After the anchor is lowered, the fixedlength of the anchor is grouted. Grouting is carried out under pressureby fixing a packer at the top of the fixed length or as necessary in accor-dance with the type of anchor. Normally thickest possible grouting
O-5 water cement ratio ) is adopted for primary grouting (see
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IS:10270 1982
distribution within the fixed length of the anchor, etc. Up to 16 percent variation isallowed compared to theoretical elongation. In any case, as far as loading on theanchor is concerned, the directly measured value as indicated by calibrateddynamometer and pressure guages is to be taken as correct.
7.CORROSION PROTECTION
7.0 he various methods of corrosion protection for minimizing corrosionof prestressed anchors are as under.
7.1 Corrosion Protection of Free Length of Anchor
4
4
4
To avoid ingress of water in the free length of anchor, agalvanized iron pipe of suitable diameter conforming mediumgrade of IS : 1239 ( Part I )-1979” is provided;
Tundon comprising of several 7 mm diameter high tensile steel
wires enclosed in a 2 mm thick suitable diameter PVC pipes isprovided. The diameter of the PVC pipe should be greater thanenclosed wires;
The annular space between the PVC pipe and the hole orgalvanized iron pipe is filled with neat cement grout; and
The wires should be painted with epoxy based paint as under:
i) High tensile steel wires are first cleaned with sand papers;
ii) Immediately afterwards, a coat of suitable primer is uniformlyapplied by brush.
iii) When the coat of primer is sufficiently dry, a coat of epoxybased paint is given uniformly.
NOTE- The base paint and thinner are so proportioned that smooth brushingis possible.
7.2 Corrosion Protection of Fixed Length of Anchors - This isdone by one or more of the following:
4
b)
The fixed length of the anchor is grouted using neat cementrepeatedly under pressure to obtain the permeability of under 3lugeons for the surrounding strata. This reduces the ingress of *
water and prevents corrosion.
The fixed length is treated with epoxy formulation ( see IS : 8230-
1976? ) as under:
i) Pretreatment - The high tensile steel wires are first pretreatedby sand blasting or grit blasting process. Thereafter, the wiresare cleaned thoroughly by using thinner.
*Specification for mild steel rubes tubulars and other wrought steel fittings: Part I(JOWh revision ) .
TSpecification for steel-filled epoxy resin based adhesives.
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IS:10270- 1982
ii) The first coat of epoxy formulation is applied uniformly on theprestressed wires and it is allowed to dry for a period of 2 to3 hours. The second coat is applied thereafter and the sameis allowed to dry for 24 hours. This is then roughened bysand paper and the third coat is then applied uniformly.
While the third coat is still tacky, quartz sand is sprinkledover it to increase the bond.
c) Additional high tensile wires can be provided to account forlong term corrosion. The number of extra wires, however, thatcan be provided depends on the diameter of anchor hole. Byprovision of extra wires, in effect, the stresses in each wire arereduced which prevents to a large extent stress corrosion as well.
8. TESTING OF ANCHORS
8.1 Water-Proofing - The anchorage length ( fixed length ) for allpermanent anchors has to be tested for water-proofing to avoid corrosion.Water tests are normally carried out by fixing a packer at the top of thefixed length or top of holes and conducting the test under pressure.Normally if the water loss is less than 3 lugeons, the hole is consideredto be satisfactory and where salinity in the grout is high, minimumacceptable permeability value is taken as 1 lugeon.
8.2 Strength - During the stressing operation 100 percent anchors arestressed to 10 percent over design load to check their sunability.
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16 : 10270 - 1982
Continuedfrom page 2 j
Miscellaneous Foundations Subcommittee, BDC 43 : 6
onvener
SHRI SHITALA SHARAN
Representing
UP State Bridge Construction Corporation,Lucknow
Members
SHRI E. T. ANTIASHRI N. C. DUGGAL ( Alternate )
SHRI S. P. CHAKRABORTI
DIRECTOR, HRSJOINT DIRECTOX R ITs E A R c 11
GE-II), RDSO
JOINT DIRECTOR STANDARD
The Concrete Association of India, Bombay
Ministry of Transport and Shipping ( Roads Wing )Highways Research Laboratory, MadrasMinistry of Railways
( B & S/CB ), RDSO ( Alternate )
SHRI S. MUKHERJEE Cemindia Company Limited, BombaySHRI B. K. PANTHAKY Hindustan Construction Co Ltd, BombaySHRI P. G. RAMAERISHNAN Engineering Construction Corporation Limited,
MadrasSHRI G. B. SINGH Alternate )
SHRI B. G. RAO Central Buildings Research Institute ( CSIR),Roorkee
SHRI M. R. SONEJA ( Alternata )SIIRI S. A. REDDI Gammon India Limited, Bombay
SHRI G. R. HARIDAS Alternate)SERI A. K. SARKAR Public Works Departmcnr, Government of West
Bengal
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INTERNATIONAL SYSTEM OF UNITS SI UNITS )
Base Units
QUANTITY
Length
Mass
TimeElectric current
Thermodynamictemperature
Luminous intensity
Amount of substance
Supplementary units
QUANTITY
Plane angle
Solid angle
Derived Units
QUANTITY
Force
Energy
Power
Flux
Flux density
Frequency
Electric conductance
Electromotive forcePressure, atress
UNIT
metre
kilogram
secondampere
kelvin
candela
mole
UNIT
radian
steradian
UNIT
newton
joule
watt
weber
tesla
hertz
aiemens
voltPascal
SYMBOL
m
kg
sA
K
cd
mol
SYMBOL
rad
*r
SYMBOL
J”W
Wb
T
117.
S
VPa
DEFINITION
IN = 1 kg.m/ss
1J = 1 N.m
1W * 1 J/s1 Wb = 1 v.s
1T * 1 Wb/ms
1 Ha = 1 c/s (I-‘)
1 s - 1 A/V
1v = 1 W/A1 Pa = I N/m’
INDIAN STANDARDS INSTITUTION
Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002
Telephones : 26 60 21, 27 01 31
Regional Offices
Western : Novelty Chambers, Grant Road
Eastern : 5 Chowringhee Approach
Southern : C. I. T. CampusNorthern : B69, Phase VII
Telegrams : Manaksanstha
Telephone
BOMBAY 400007 37 97 29
CALCUTTA 70007? 27 50 90
MADRAS600113 41 24 47S.A.S. NAGAR
-MOHALI ) 160051
6ranch OffIces:
‘Pushpak’, Nurmohamed Shaikh Marg, Khanpur
‘F’ Block, Unity Bldg, Narasimharala Square
Gangotri Complex, Bhadbhada Road, T. T. Nagar
22E Kalpana Area
5-8-56C L. N. Gupta Marg
.il 14 Yudhister Marg, C Scheme
1171418 B Sarvodaya Nagar
Patfiputra Industrial Estate
Hantex Bldg 2nd Floor j. Rlv Statlon Roa6
AHMADABAD 380001 2 03 91
BANGALORE 560002 22 48 05
BHOPAL 462003 6 27 16
BHUBANESHWAR 751014 5 36 27
HYDERABAD 500001 22 1 a3
JAIPUR 302005 6 98 3’
KANPUR 208005 4 72 92
PATNA 800013 6 28 08
TRIVANDRUM 695001 32 27
Printed at Arcee Press, New Delhi, India
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AHENtMENT NO. 1 P4ARCH1985
TO
I S:10270- 1982 GUI DELI NES FOR DESI GN AND CONSTRUCTI ONOF PRESTRESSED ROCK ANCHI RS
(Page
a)
b)
7, c us 5.2.2):
Lines land 5 - Substitute the wurd ‘Fixed’
fOP 'Free'.
Line 6 - Substitute the olr>rdsaddit ons1fixed' or 'free'.
Page 9, Tabte I, St No.(vii), cob 31 - Substitute
?e 11, ChMe 7.1(b)] - Substitute 'Tend-'for 'Tandon'.
Pages 10 and I I , cl auee 6. 7, Note) - Add the
following at the end:
*The factors such as relaxation of wires and creep willbe considered before the anchor is finally Locked and
grouted. For this, once the anchor is locked at the
design load, it will be kept undisturbed for minimum
seven days or till one day after the last anchor has
been stressed in a particular unit, whichever is later
and then checked for the losses due to relaxation,
creep, etc, for the individual an cho r . The anchor is
then restressed to the design load and free length of
anchor ie finally grcuted. Certain type of anchordesigns are possible in which free length is enclosed
in plastic sheathing, it is however en su r ed that no
grout should come in contact with the steel in the
fixed length portion of the anchor. Due to
prestressing force the settlement/movement of the
structure itself can be meafured by placing 3 dial
gauges around the anchor head.'
BDC 43)
Reprography Unit, ISI, New Delhi, India
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AMENDMENT NO. 2 DECEMBER 1988
TO
KS : 10270-1982 GUIDELINES FOR
DESIGN AND CONSTRUCTION OF PRESTRESSEDROCK ANCHORS
[ Page 6, clause 3.1 c) 1:
i) Line 4 - Substitute ‘ IS : 1892-1979* ‘for c IS : 1982-1972* ‘.
iv) Line 2 - Substitute ‘ 2720 ( Part 22 )-1972 ’ for ‘ IS : 2720Part 22 )-1977 ‘.
v) Lines 2 and 3 - Substitute ‘ IS : 5529 ( Part 2 )-1985 for’ IS : 5529 ( Part 2 )-1973 ‘.
( Page 6, foot-note marked with ‘ 7 ’ mark j - Substitute the followingfor the existing foot-note: .
‘TCode of practice for iu si6u permeability tests: Part 2 Tests in bedrocks J irst
rcuision ) .’
Page 7, clause 4.2 ) - Substitute ‘ IS : 2090-1983 ‘fur ‘ IS : 20’30-
1962 : ‘. .
Page 8, clause 6.3, line 3 ) - Substitute ‘ IS : 6066-1984 ’ for IS :
6066-1971 ‘.
( Page 10, clause 6.6, line 1 ) - Substitute ‘ IS : 6066-1984* ‘for‘ IS : 6066-1971* ‘.
( Page 10, clause 6.7, lins 1 ) - Delete the word ‘ by ‘.
( Pages 8 and 10, foot-note marked with ‘ * ’ mark ) - Substitute the
following for the existing foot-note:
“Recommendations for pressure grouting of rock foundations in river valley
projects first rsui si on .
(BDC43)
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