Diaphragm Wall Construction Work

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Diaphragm Wall Work forDiaphragm Wall Work for

the Proposed Residential Developmentthe Proposed Residential Development


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Project DescriptionProject Description

Approximate Value: HK$214M

Contract Duration: 390 days

Commencement Date : 03 May 2010

Completion Date: 27 May 2011

Client: Sino Group / Hopewell Holdings

Ltd. / URA

Consultant: CM Wong

Main Contractor: Gammon Construction Ltd


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IntroductionIntroduction

Diaphragm Wall is generally reinforced concrete

wall constructed in the ground using under slurry

technique which was developed in Europe. e tec nique invo ves excavating a narrow trenc

that is kept full of an engineered fluid (Bentonite) of

slurry.

Walls of thickness between 300 and 1200 mm can

be formed in this way up to a depth of 45 meters.


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Advantage of Diaphragm WallAdvantage of Diaphragm Wall

Diaphragm walls are underground structural

elements commonly used as retention systems and

permanent foundation walls. They can also be used

as groundwater barriers. The primary advantage of

a diaphragm wall over a secant wall is the reduced

number of joints in the wall which ultimately

improves the walls water tightness. Diaphragm walls

tend to be used for retaining very deep excavations

as they can be designed to take very high structural

loads.


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Conceptual sketch showing the RCC Diaphragm WallConceptual sketch showing the RCC Diaphragm Wall

Excavation of

Panel

Installation of

Rebar Cage

Concreting

of Panel


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Project DescriptionProject Description

Scope of Work:Scope of Work:

Bored Piles WorkBored Piles Work

Diaphragm Wall WorkDiaphragm Wall Work

Utilities DiversionUtilities Diversion

Hoarding ModificationHoarding Modification


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Project Description (Diaphragm Wall Work)Project Description (Diaphragm Wall Work)

Total LengthTotal Length : 420m (approximate): 420m (approximate)

ThicknessThickness : 800mm, 1000mm and 1200mm: 800mm, 1000mm and 1200mm


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Construction SequenceConstruction Sequence

Grout Curtain WallGrout Curtain Wall

Near Historical BuildingNear Historical Building

Diaphragm Wall ConstructionDiaphragm Wall Construction

Contact Grout (for Load Bearing Panels only)Contact Grout (for Load Bearing Panels only)

Shear Pin InstallationShear Pin Installation


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Near Historical BuildingNear Historical Building

TubeTube--AA--Manchettes (TAM) Grouting MethodManchettes (TAM) Grouting Method

Spacing @ 1.5 c / c down to rockhead /Spacing @ 1.5 c / c down to rockhead / --40mPD40mPD


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Carry out in Rises from the bottom upCarry out in Rises from the bottom up

to Exiting Ground Levelto Exiting Ground Level

Grout in 2 stagesGrout in 2 stages

BentoniteBentonite -- Cement GroutCement Grout

Chemical GroutChemical Grout

(Solution A + Solution B)(Solution A + Solution B)


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Total LengthTotal Length :: 420m (approximate)420m (approximate)

ThicknessThickness :: 800mm, 1000mm and 1200mm800mm, 1000mm and 1200mm

Total PanelTotal Panel : 83no.s: 83no.s

Normally construction period :Normally construction period :

around 7 ~ 10 days for eacharound 7 ~ 10 days for each


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Wall ThicknessWall Thickness 800mm, 1000mm and 1200mm800mm, 1000mm and 1200mm

Type of DType of D--Wall PanelWall Panel Load Bearing Panel /Load Bearing Panel /

NonNon--Loading Bearing PanelLoading Bearing Panel

Panel DepthPanel Depth Type 1:Type 1: --1212 mPDmPD

Type 2:Type 2: --2020 mPDmPD

Type 3:Type 3: --2727 mPDmPD

Type 4:Type 4:-- 2525 mPDmPD

500mm key500mm key--in into Bedrockin into Bedrock

(Grade III/IV)(Grade III/IV)

non-loadbearing

load /non-loadbearing


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Elevation View AElevation View A

VIEW AVIEW A

+5.0+5.0

+0.0+0.0

--5.05.0

--10.010.0

--15.015.0

--20.020.0

--25.025.0

--30.030.0

Grade III / IVGrade III / IV


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Elevation View BElevation View BVIEW BVIEW B

+5.0+5.0

+0.0+0.0

--5.05.0

--10.010.0

--15.015.0

--20.020.0

--25.025.0

--30.030.0

--35.035.0

--40.040.0

--45.045.0

--50.050.0

--55.055.0

Grade III / IVGrade III / IV

SoilSoil


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Elevation View CElevation View C

VIEW CVIEW C

+5.0+5.0

+0.0+0.0

--5.05.0

--10.010.0

--15.015.0

--20.020.0

--25.025.0

--30.030.0

--35.035.0

--40.040.0

--45.045.0

--50.050.0

--55.055.0 Grade III / IVGrade III / IV

SoilSoil


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Guide Wall ConstructionGuide Wall Construction

EnsureEnsure TrenchTrench ExcavationExcavation RemainsRemains withinwithin AllowableAllowable ToleranceTolerance

SupportSupport ReinforcementReinforcement Cages,Cages, TremieTremie PipesPipes andand OtherOther EquipmentEquipment

MaintainMaintain BentoniteBentonite MudMud LevelLevel


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Diaphragm Wall ExcavationDiaphragm Wall Excavation

UsingUsing ClamshellClamshell toto ExcavateExcavate SoilSoil

DifferentDifferent ThicknessThickness toto SuitSuit DD--WallWall ThicknessThickness


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HydromillHydromill

UsingUsing CutterCutter forfor ExcavationExcavation

AdjustableAdjustable CutterCutter ThicknessThickness toto

SuitSuit DD--WallWall ThicknessThickness


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ControlledControlled ChiselingChiseling forfor RockRock SocketSocket

andand RemovalRemoval ofof ObstructionsObstructions


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Joint CleanerJoint Cleaner


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Stopend and Waterstop InstallationStopend and Waterstop Installation


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RemoveRemove SoilSoil DebrisDebris ininthethe returnedreturned BentoniteBentonite

DesandingDesanding


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LapLap Length,Length, StartersStarters //CouplersCouplers LocationLocation AreAreClearlyClearly MarkedMarked onon SteelSteelCagesCages

StartersStarters // CouplersCouplers AreAre

Steel Cage InstallationSteel Cage Installation

ConnectionConnection ofof SteelSteel

CagesCages byby UU--boltsbolts


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PouringPouring ConcreteConcrete toto CompleteCompletethethe PanelPanel byby TremieTremie MethodMethod

Concreting of PanelConcreting of Panel


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Typical Panel ArrangementTypical Panel Arrangement

WATER

STOP

STOP

END


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Contact GroutContact Grout

CarriedCarried outout forfor LoadingLoading PanelPanel OnlyOnly

DrillDrill ThroughThrough ReservationReservation TubeTube toto aa

DepthDepth 11mm belowbelow ToeToe ofof DD--WallWall

CarryCarry outout ContactContact GroutGrout toto ProvideProvide

GoodGood ContactContact betweenbetween DD--WallWall //

BedrockBedrock


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Shear Pin InstallationShear Pin Installation


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Provision of Shear PinProvision of Shear Pin

RockheadRockhead wouldwould bebe encounteredencountered atatmuchmuch shallowershallower depths,depths, AsAs such,such, duedue totothethe difficultiesdifficulties forfor excavationexcavation intointo rockrockforfor thethe constructionconstruction ofof diaphragmdiaphragm wall,wall,

shearshear pinpin isis adoptedadopted asas anan extensionextension ofofap ragmap ragm wawa n on o e roce roc en anceen ance

thethe toetoe stabilitystability ofof thethe DD--wallwall..


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Inspection and TestInspection and Test

Tests and Inspections Acceptance Criteria Frequency Method of Inspection

Setting Out D-Wall thickness +/-50mm Every Panel Surveying

D-Wall Rockhead Level As stated in drawing Every Panel Visual Inspection

D-Wall Toe Level As stated in drawing Every Panel Measuring tap

Fabrication of Steel Cage As stated in drawing Every Cage Measurement

Verticality Test 1:80 Every Panel Lowering of Chisel

Bentonite Testing Stated in drawing - Stated in drawing


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Verticality ControlVerticality Control

LoweringLowering ChiselChisel

inin DD--WallWall TrenchTrench

forfor CheckingChecking


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Testing of BentoniteTesting of Bentonite

Property to be Measure Test Method & Apparatus Fresh Bentonite Prior to Concreting Re-use

Density (g/ml) Mud Balance 1.01 to 1.03


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Monitoring (Bentonite Slurry Level)Monitoring (Bentonite Slurry Level)

ImmediateImmediate LossLoss ofof BentoniteBentonite SlurrySlurry duringduring ExcavationExcavation

PossiblePossible ResultResult inin TrenchTrench StabilityStability

TrenchTrench toto bebe ImmediatelyImmediately BackfilledBackfilled withwith ExcavatedExcavated SoilSoil


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Monitoring (Alert / Alarm / Action Level)Monitoring (Alert / Alarm / Action Level)

Alert Level Alarm Level Action Level

Ground Settlement Check Point (Sensitive) 5mm 8mm 12mm

Ground Settlement Check Point (General) 15mm 20mm 25mm

Buildin Settlement Check Point Sensitive 5mm 7mm 10mm

Building Settlement Check Point (General) 8mm 10mm 15

Vibration Check Point 3mm/s 5mm/s 7.5mm/s

Piezometer - 0.4m drop 0.5m drop

Tilting 1:1000 1:750 1:500

Water Main Check Point 10mm 15mm 20mm


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Sonic Logging TestSonic Logging Test

TheThe SonicSonic LoggingLogging TestTest cancan bebe thethe mostmost suitablesuitable methodmethod toto detectdetect thetheconcreteconcrete defectsdefects ofof thethe diaphragmdiaphragm wall,wall, suchsuch asas honeycombinghoneycombing duedue totoinadequateinadequate vibration,vibration, segregationsegregation duedue toto overover vibrationvibration andand improperimproperconcreteconcrete placementplacement method,method, washwash outout ofof cement,cement, crackscracks inin thethe wallwall..Therefore,Therefore, efforteffort mustmust bebe takentaken toto ensureensure eacheach wallwall buildbuild upup onon sitesite toto bebefreefree fromfrom anyany kindkind ofof defectsdefects duringduring thethe constructionconstruction..


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Interface Coring TestInterface Coring Test

TheThe purposepurpose ofof thethe testtest isis toto verifyverify thetheinterfaceinterface conditioncondition ofof thethe concreteconcrete andandbedrockbedrock..


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Daily Progress Report for Monitoring ofDaily Progress Report for Monitoring of

Diaphragm wallDiaphragm wall


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Daily Progress Report for Monitoring ofDaily Progress Report for Monitoring of

Diaphragm wallDiaphragm wall


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Thank YouThank You

Diaphragm Wall Construction Work

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