METHOD OF SUPPORTING AN EXCAVATION FOR BASEMENT CONSTRUCTION

METHOD OF SUPPORTING AN EXCAVATION FOR BASEMENT CONSTRUCTIONNUR AQILA EZZANY BINTI KAMARULZAMANNUR AZIMAH ADILA BINTI MOHD SHUKRISAKINAH KHALIDAH BINTI KAHARUDDINSITI NADIRAH BINTI JAMILINTRODUCTIONDefinition Basement:Abasementexcavationis a construction dig.

There are several common method of excavation, in order to build basement.

Essential that the excavation is adequately supported, and the groundwater properly controlled.SELECTION OF EXCAVATION FOR BASEMENT CONSTRUCTIONSubsoil conditions and ground water level

Working space requirements and site constraintsMaintenance of the wall and support system in permanent condition

Cost and times of construction

Local experience and available construction plant

a form of driven piling using thin interlocking sheets of steel.Used vibrating hammer, t-crane and crawler drilling to establish itsuitable for sites where the space around the excavation is insufficient for sloping back the sidesSHEET PILE WALLSHEET PILE WALLIt consist of rolled steel sections with interlocking edge jointsThe interlocking edges allow each sheet pile to slide into the next with relative ease.

METHODS OF CONSTRUCTION SHEET PILE

1) POSITION OF STEEL

2) INSTALLATION OF FIRST SHEET PILE

3) INSTALLALTION OF SECOND SHEET PILE

4) REPITATION OF PROCESS

5) EXTENSION OF SHEET PILEExamples of Sheet Pile

ADVANTAGESDISADVANTAGESRapid installationDirect driving effect on the subsoilSteel can be either permanent or recoveredNoisy very economical compare with the alternative of a diaphragm wallHigh capital investment if re-usage is restrictedSeal may not be perfectConstructed by excavation in a trench which temporarily supported by bentonite slurry.Suitable for :sites where obstructions in the ground prevent sheet piles from being driven where the occurrence of groundwater is unfavorable for other methods of support.Also suitable for sites where considerations of noise and vibrationOn reaching founding level steel reinforcement is lowered into the trench, followed by concrete to displace the bentoniteDIAPHRAGM WALLMETHODS OF CONSTRUCTION DIAPHRAGM WALL

1 ) Construction of Guide Wall

2 ) Excavation of Panel2. EXCAVATE TRENCH

3) Installation of Rebar Cage4) Concreting of Panel

5) Repetition of ProcessExamples of Diaphragm Wall

ADVANTAGESDISADVANTAGESPermanent basement wallA lot of labour is neededScan be designed to form part of a permanent foundationLong period of constructionMinimum vibration and noiseHigh cost Can be used in restricted spaceCONTIGUOUS PILE WALL line of bored pile installed close together or touching. Smaller diameter micro-pile may be installed in between each adjacent pile.

Gaps between the micro-pile and main piles are grouted. METHODS OF CONSTRUCTION CONTIGUOUS BORED PILE

1). POSITION OF BORED PILE

2) INSTALLATION OF CASING VIBRO HAMMER

3) AUGERING OF BORE PILE

4) INSTALLATION OF STEEL CAGE

5) CONCRETING OF BORE HOLE

6) EXTRACTION

7) REPITATION OF PRECESSExamples of Contiguous Bored Pile

Advantages

Disadvantages

Built-up areas where noise and vibration should be limitedConcrete in shaft susceptible to squeezing or necking in soft soil where conventional types are usedIn industrial complexes where access, headroom and/or restriction on vibration may make other methods such as steel sheet piling or diaphragm walling less suitableSpecial techniques needed for concreting in water bearing soilsLower costConcrete can be readily inspected after installationSpeed in construction for temporary and permanent wall where drilling conditions are conducive Drilling a number of pile in group may cause loss of ground and settlement of adjacent structuresHigher capacity to overcome obstruction like rock compare to other system Additional work are needed to form an acceptable surface to the wallDrilling tools can be break up boulders or other obstructionsLack of water tightnessSecant pilesimilar to contiguous bored piles except that they are constructed in:- male - female

interlock each other. male piles are reinforced while the female piles are not. In cases where lateral pressure from the soil is excessively high, male-male secant piles may be used.

METHODS OF CONSTRUCTION SECANT PILE

1. CONSTRUCT A GUIDE WALL

2. INSTALLATION OF STEEL CASING

3) AUGERING OF PRIMARY BOREHOLES

4) CONCRETING OF PRIMARY BOREHOLES

5) AUGERING OF SECONDARY BOREHOLES

6) INSTALLATION OF STEEL CAGE

7) CONCRETING OF SECONDARY BOREHOLE

8) REPITATION OF PROCESS

Example Secant Pile..

AdvantagesDisadvantagesProvide higher degree of water tightnessHigh cost for installationStronger resistance to lateral pressureEnsuring complete contact of all piles over their full length Can be used on small and confined sitesMay be difficult in practiceSuitable to built near building, roads and other sensitive structuresMinimum noise and vibrationCASE STUDY CONTRACT TITTLE Purpose to build 33 storey office tower developed by KL Sentral & MRCB for Lembaga Tabung Haji

SCOPE OF WORKS 1 BLOCK OFFICE WHICH CONSISTS OF : - 3 levels of basement parking - 2 levels of Main lobbies - 5 levels of elevated car parks - 1 level of M&E Floor - 20 levels of Offices - 2 levels of Penthouse

PROJECT BRIEFING Location of site : KL Sentral Located at congested area ( Putra,KTM,Erl station,shop lots building, private parking area,hotel, office building, etc ) The land is existed flat According to soil engineer, type of soil consist : sandy clay, silty clay, silty sand, shale and shale rock.- It was busy area within working hoursNATURE OF SITEMETHOD STATEMENT OF BASEMENT WORKS SURVEY STAGE - Land surveyor play their role the original ground level and set out control point SITE CLEARING - demolition of existing building small shop building - grubbing out bushes, trees and removal soil to reduce level - After site clear - hoarding, wash trough, storage and temporary site office CONSTRUCTION OF DIAPHRAGM WALL AND CONTIGUOUS BORED PILE

- two type of retaining wall has decided by engineer diaphragm wall and contiguous bored pile. - use existing diaphragm wall save cost and limited space ( refer layout plan) - reason : if build new diaphragm wall, ground anchor fixed to diaphragm wall will disturbed the foundation of existing building - use contiguous bored piled - For perimeter area did not have existing building - Bored piled : - total used : 260 nos - size : 750 mm - depth : 16 m - gap : 75 mm - use helical reinforcement - I machine can build only 2 bored pile in one day have 4 machine at site - after completion, use concrete 200 mm thk as skin wall + waterproofing - advantages using contig.bored pile : It is free standing didnt use anchor

EXCAVATION - after completion of diaphragm wall and contiguous bored pile, excavate basement. - excavate 10.00 m depth - use 1m3 bucket excavator. - ramp system purpose of transportation loading and unloading construction material.( refer figure 5.19 ) - the ramp will remove after excavation process. - temporary opening entering excavation area ( refer figure 5.20 )

CONSTRUCTION TECHNOLOGY IV - BASEMENT CONSTRUCTION BASEMENT FOUNDATION - use raft foundation as a foundation - depth : 2.75 m - size of reinforcement : 25 mm , 32 mm - concreting process concrete + ice cube low the temperature - reason use raft foundation : - carry a great load - soil hard material at site

View 1 raft foundation construction

View 5 Concreting of raft in progress

View 6 completion of concretingRaft foundation CONSTRUCTIONN OF BASEMENT FRAME AND STRUCTURE

- method of construction : bottom up method ( refer figure below ) - starting by construction of basement column - start from B1 - B2 B3 - construction including concrete, formwork , reinforcement Construction of Basement Frame

BACKFILLING - after completion of basement frame backfilling process - backfilling process by stage - after completion of B3, contractor constructing B2 level backfilling process proceed at level B3 - repeat backfilling sequence until upper levelBackfilling the remaining excavated area

COMPLETE BASEMENT - after backfilling process structural work for basement completely finished - proceed upper level construction floor , wall, etc.Complete Basement

conclusion Whichever method supporting basement chosen and any consideration will have to be given to additional measures to achieve good performance corresponding to modern consumer expectations.

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