DIAPHRAGM WALL CONSTRUCTION
(Extracted from Sambo Catalogue unless otherwise stated)

 

Overview


A typical snap shot of a diaphragm wall construction site. The cylindrical steel tanks are for storage of bentonite slurry.

 


Equipment for diaphragme wall construciton: bentonite, mixer, desanding..., for a reverse circulation system

 


Schematic circulation system (from Bauer catalogue)

 

1. Install guide wall 2. Trench excavation and deposit soil to a holding tank
3. Install rebar cage 4. Checking verticallity by Coden Test
5. Tremie concrete 6. Disposal of excavated soil from holding tank
Typical work sequence of a diaphragm wall panel

 

Construction Sequence


Rebar fabrication

 


Stop end sheet pile fabrication for holding up waterproofing rubber band

 


Construct guide wall (about 1.5 to 2m depth and 0.4m wide). Normal shape like ¬ to form half of the guide wall. Guide wall is not only used for D wall machine excavation, but also servers as working platform duration D wall operation.

 


Pre-excavation to clear surface and shallow (up to 10m deep) obstacles of a panel trench by a hydraulic grab

 


Trench excavation by a mechanical grab (clamshell grab). For excavation into hard soil at deeper level, cutter or drilling bit is to be used. Typical panel is 3-6m in length.

 


Trench excavation in progress (DTL2 Little India Station)

 


Install rebar cage

 


Install upper part of rebar cage to join the lower one

 


Tremie concreting. Bentonite is being pumped back to the recycle system.

 

Joint Types

There are three joint types: the conventional stop end tube or sheet pile, and the overlap cutter joint.

 

1. Fabrication of end plate 2. Join 2 end plates
3. Attach waterproofing rubber band to the plate 4. Install end plate

Stop-end sheet pile attached with waterstop: work sequence

 


Stop-end plate: plan

 


Stop-end plate: Fabrication

 


Stop-end plate: close view

 


Overlap cutter joint

CROSS REFERENCE:
Piling and Diaphragm Wall Machines