g&p digest issue 6

8/12/2019 G&P Digest Issue 6

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G&P DIGESTNewsletter of G&P Professionals Group

Issue 6 : J

In this Issue:In this Issue:

ELECTRIFIED DOUBLE TRAC K ELECTRIFIED DOUBLE TRAC K

Ground Treatment Design foGround Treatment Design fo

-- Ipoh to PadangIpoh to Padang BesarBesar

KLANG VALLEY MRT UNDERGKLANG VALLEY MRT UNDERG

Deep Excavation on LimestoDeep Excavation on Limesto

-- Cochrane StationCochrane Station


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Ground Treatment Design for

200km Electrified Double Track Railway Project inNorthern Peninsular Malaysia

IntroductionThe Malaysian Government has decided to extend theelectrified double track railway from Ipoh to Padang Besar inPeninsular Malaysia. The electrified double track railwaygenerally follows the alignment of the old railway line from Ipohto Padang Besar with a total distance of 350km as shown inFigure 1. G&P is the consultant engaged by MMC-Gamuda

J oint Venture Sdn Bhd to design the ground treatment for abouta 200km stretch of the electrified double tracks from PadangRengas to Alor Setar. The design speeds for passenger train and

freight train are 180km/hour and 90km/hour respectively. Thedesigned axle loads are 20 tonnes and 16 tonnes for passengerand freight trains respec tively.

4

G&P

involved

in ground

treatment

design for

200km

long

Electrified

Double

Tracks

Railway.

The ChallengesAs the railway tracks transverse a distance of 200km from north to south going through various

geological formations, (Figures 2 and 3), the subsoils vary from soft alluvium deposits to denseresidual soils.

In addition, the geometrical tolerance of railway tracks is very stringent, espec ially for trains withhigh a design speeds of 180km/hour. The design performance requirements include differentialsettlement of not more than 10 mm over a chord length of 10m and settlement of not more than25mm within 6 months after completion.

Hence, various ground treatment designs are required to meet the performance requirements andconstruction schedules are required, especially when long stretches of the embankment supportingthe tracks are traversing very soft to soft alluvium deposits with thickness of 15m to 20m.

Figure 1: Loca tion o f Electrif ied Doub le Trac ks Railwa y

Figure 2: Ge neral G eo logy fo r Electrif ied Doub le Trac ks Railwa y from Bukit

Mertajam to Alor Setar

2Geotechnical | Civil & Structural | Infrastructure | Flood Mitigation

Highway & Transportation | Mechanical & Electrical | Hydrology & HydraulicMaritime | Dam | Claims & Contract | Project Management

Figure 3: Gene ral Geo logy for Electrif ied Doub le Trac ks Railwa y from Butterworth to

Pad ang Renga s


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3G&P Professionals Group is a specialist one-stop engineering consultancy service centre that providesengineering services in various areas of buildings, infrastructure and heavy engineering with staffstrength of over 250 people.

Design for Embankments

Settlement AnalysesConstruction of embankments will causesettlement to take place in the subsoil duringand after filling especially for soft clay.

Therefore, it is necessary to evaluate themagnitude and rate of settlement of thesubsoil supporting the embankments. Thedesign concept is shown in the adjacentfigure. It is of utmost importance to ensure longterm settlement is within the acceptabletolerance.

Stability AnalysesThe stability of the embankment is assessedwith consideration for different potential failuremechanisms namely circular (Modified BishopMethod) and non-circular (Modified J anbuMethod). The Factor of Safety (FOS) duringconstruction is 1.2 and the FOS for long term is1.4.

Dynamic Analyses

Other than stability analyses (static effect),dynamic effect analyses were also carried outto determine the safe configuration of therailway embankment in order to preventexcessive subgrade deformation and failuresdue to repetitive axle loads.

Empirical formulae based on speed, probabilityfactors and track conditions are adopted forthe computation of the Dynamic AmplificationFactor (DAF)

Undrained Shea r Strength Req uired for Dyna mic Stress Effec t

Embankment Behaviouron Soft GroundThe behaviour of an embankments Factor ofSafety and pore water pressure changes on softground are most critical (highest risk of failure)during filling and least critica l (lowest risk offailure) in the long term during the operation of

the embankment track.

DYNAMIC STRESS: Su at Ground Surface Vs Height of Embankment

0

20

40

60

0.0 2.0 4.0 6.0 8.0 10.0

Height of Embankment (m)

Undrained

ShearStrength

(kPa)

Passenger Train Freight Train

The Factor of Safety of embankment over softground against excess pore water pressure isshown in the adjacent figure, which showshighest risk of failure at the end of filling.


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4 Geotechnical | Civil & Structural | Infrastructure | Flood MitigationHighway & Transportation | Mechanical & Electrical | Hydrology & Hydraulic

Maritime | Dam | Claims & Contract | Project Management

Ground Treatment Design

Use of Ground TreatmentGround treatments are used to fulfill the specified settlement criteria and to ensure adequate stabilityof embankment and prevent collapse. Generally, some ground treatments are required in soft groundareas due to its high compressibility and low bearing capacity.

Adopted Ground Treatment Techniquesa) Excavation & Replacement of Soft Soil

Typ ic a l Cross Sec t ion a nd Pho to sho wing Tem p ora ry She et

Pile f o r E&R.

b) Surcharging

c) Prefabricated Vertical Drain (PVD) d) Stone Columns

Typ ic a l PVD Ma c hine w orking b eside the Live Tra c k

Insta llat ion o f Sto ne C olum ns ad jac en t to Exist ing Live Tra c k.

ConclusionsThe basic key ingredients for a successful ground treatment to achieve the performance requirements(stability and settlement) for design and construction of high speed railway embankment area asfollows:-

Em b a nkm en t f il l w ith surcha rg e b eside exist ing live tra c ks

(a ) Awareness of project requirements and specifications(b ) Knowledge of the site and subsoil conditions(c ) Proper geotechnical design(d ) Full time proper supervision and care as well as proper monitoring of the performance of the

embankment.


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6Geotechnical | Civil & Structural | Infrastructure | Flood Mitigation

Highway & Transportation | Mechanical & Electrical | Hydrology & HydraulicMaritime | Dam | Claims & Contract | Project Management

Figure 3 shown schematic of excavation worksat Cochrane station. The selection of theretaining structure has to consider theworkability and suitability of subsoil and rockconditions. A secant pile wall was selected asthe earth retaining wall tied back with a

temporary ground anchor (Figure 4). Theadvantages of the selected wall type are (i)water-tightness to prevent groundwater draw-down on the retained side; and (ii) the abilityto vary the pile lengths to suit the irregularlimestone bedrock profiles. Secant piles of880mm and 1000mm in diameter weredesigned with an overlap of 130mm and200mm respectively representing 15-20% of pilediameter. The extent of overlapping of thesecant piles are governed by pile installation

verticality, pile deviation and pile depth.

AchievementWith proper geotechnical input, costly failure and delay assoc iated with underground works in limestoneformation such as excessive groundwater lowering, occurrences of sinkholes, excessive groundsettlement, etc. can be prevented. It is important to have continuous feedback from the constructionteam to anticipate such problems and such model of cooperation between the construction team andG&P geotechnical engineers has proven to be successful for the excavation works at Cochrane station.

Figure 3: Sc hem at ic o f exca va t ion wo rks

(Note : Actua l loc at ions an d leng th of roc k slop e

st reng then ing a re d e te rm ined a f t e r ge o log i ca l ma pp ing

wo rks a nd kine m a t ic a na lysis) .

Figure 4 : Typ ica l ar ra ng em ent of sec a nt p ile wa ll

Fissure grouting involves a single packer in ascendingor descending stages in order to inject groutsuspension into existing pathways, fissures, cavitiesand discontinuities within the rock formation. Rockfissure grouting is also adopted for base grouting atlarger grout hole spacing. If any cavities are

detected during drilling / grouting, compactiongrouting with cement mortar will be used as cavitytreatment.

De sign Tea m : (from left) Ir. Ko o K.S. , Le e Y.C , Ch ee F.W. an d

To ng H.S.

( f ron t ) Ir. Dr. G ue S.S (Ma na ging Direc tor) and

Ir. Ta n Y.C. (Pro jec t D irec to r)

The rock excavation was carried out usingcontrolled blasting with adequate protection.

The blasting works were carried out in 2 to 3mbenches. After blasting, geological mappingwas carried out by qualified geologists tocollect field data on the exposed rock faceincluding details of discontinuities, rock faceweathering conditions, etc. to determinesuitable rock strengthening works.Grouting work was also carried out forlimestone to reduce the rate of groundwater

inflow into excavation and reduce waterpathways around excavation areas.


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7G&P Professionals Group is a specialist one-stop engineering consultancy service centre that providesengineering services in various areas of buildings, infrastructure and heavy engineering with staffstrength of over 250 people.

Christmas Party being a G &P annual event was held on 20th December 2013. Some of the highlightswere Caroling, mini games as well as a memorable gift exchange session. The event was full of joyfun and exciting moments.

NEWS FLASH @ G&PChristmas Party 2012

G&P Professionals being a company emphasizingcontinuous learning and knowledge sharing hascontinuously provided various types of training toits engineers for their personal and professionaldevelopment. The G&P training committee hasorganized a site visit to an on-going project siteknown as Damansara Uptown Phase 2.

The site visit was a very beneficial experience to allengineers as it was undergoing variousgeotechnical works. Many site activities can bewitnessed, such as construction of secant pile wall,installation and stressing of ground anchor on thesecant pile wall as well as bored piles construction.

The site visit was also ac companied by a few ofour experienced engineers Ir. Darryl Fong and Ir.Loh Yee Eng for on-the-spot explanation andclarification.

Site Visit @Damansara Uptown Phase 2


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G&P Professionals Sdn BhdWisma G&P39-5, J alan Tasik Selatan 3,

Bandar Tasik Selatan, 57000 Kuala Lumpur, Malaysia.

Tel : 60(3) 9054 1612 /9059 5396 Fax : 60(3) 9059 5869

Email: [email protected] www.gnpgroup.com.my

Discla imer: While every effort has been taken in this publication to ensure that the information is ac curate and up to date, G&P makes nowarranty, representation or undertaking whether expressed or implied, nor does it assume any legal liability, whether direc t or indirect, or

CORPORATE PROFILEG&P Professionals Group consists of the followingspecialist engineering consulting firms that providea wide range of quality engineering services:

G&P Geotechnics Sdn. Bhd.

G&P Structures Sdn. Bhd.

G&P Infra Sdn. Bhd.

G&P Maritime Sdn. Bhd.

G&P Claims & Contracts Sdn. Bhd.

G&P Project Management Sdn. Bhd.

G&P Water Sdn. Bhd.

G&P R International (Cambodia) Co. Ltd.

G&P Highways & Transportation Sdn. Bhd.

G&P Dams & Water Services Sdn. Bhd.

G&P Professionals (Sarawak) Sdn. Bhd.

NGI - G&P Sdn. Bhd.

G&P Water (Singapore) Pte. Ltd.

G&P - AA International Consultant J oint Stock

Company, Vietnam

G&P Professional (Sabah) Sdn. Bhd.

G&P R&D Sdn. Bhd.

G&P M&E Sdn. Bhd.

G&P Special Structures Sdn. Bhd.

The Group has a fast expanding pool of highlyqualified and experienced Geotechnical, Civil &Structural, Mechanical & Electrical, Infrastructure,Maritime, Water, Highways, Railways &

Transportation and Dams Engineers, EngineeringGeologists and technical support staff.

The Group has several assoc iated organisationsoverseas where value added is further enhanced.

The project activities are handled by the specialistswithin the Group who explore innovative andeconomical solutions tailored to the needs of theprojects. Our research and development culturehas ensured that our services are always at theforefront of world trends.

Associated Organisation

G &P P R O F E S SI O N A L S G R O U P O F C O M P A N I E S

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g&p digest issue 6

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