Diaphragm Wall

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Diaphragm Wall (Strip Piles) Ahmed Osama Khattab Ahmed Osama Khattab Ahmed Hussien Moharram Ahmed Hussien Moharram Mohamed Hatem Shams Mohamed Hatem Shams Mohamed Osama Amin Mohamed Osama Amin Mohamed Yousry Mohamed Mohamed Yousry Mohamed

Transcript of Diaphragm Wall

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Diaphragm Wall(Strip Piles)Ahmed Osama KhattabAhmed Osama Khattab

Ahmed Hussien MoharramAhmed Hussien MoharramMohamed Hatem ShamsMohamed Hatem ShamsMohamed Osama AminMohamed Osama Amin

Mohamed Yousry MohamedMohamed Yousry Mohamed

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ContentsContents• Introduction to the sitesIntroduction to the sites• Problems faced.Problems faced.• Sequence of Construction.Sequence of Construction.– Diaphragm wall construction.Diaphragm wall construction.– Soil injection (plugging).Soil injection (plugging).– Excavation and Dewatering.Excavation and Dewatering.– Slab Construction.Slab Construction.

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Introduction to The Sites

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The SitesThe two sites we covered are:The two sites we covered are:• The Ventilator in Khalifa El-Maamoun The Ventilator in Khalifa El-Maamoun

Street (Diaphragm Wall work was Street (Diaphragm Wall work was done)done)

• The Station in Marghany Street The Station in Marghany Street (Diaphragm Walls are under (Diaphragm Walls are under construction)construction)

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Ventilator Plans

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Problems

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Problems• Very deep construction (up to 35 m in Very deep construction (up to 35 m in

depth)depth)• High water table (3 m below ground High water table (3 m below ground

level)level)• Connecting the slabs’ reinforcement Connecting the slabs’ reinforcement

to the smooth diaphragm wallsto the smooth diaphragm walls• Slab construction sequence:Slab construction sequence:• Bottom to topBottom to top• Top to bottomTop to bottom

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Building Sequence

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• Diaphragm wall constructionDiaphragm wall construction• InjectionInjection• Excavation and dewateringExcavation and dewatering• Slab constructionSlab construction

Construction Sequence

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Equipment:

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The HydrofraiseThe Hydrofraise• The hydrofraise is used to dig deep The hydrofraise is used to dig deep

rectangular wallsrectangular walls• The Hydrofraise suspends the The Hydrofraise suspends the

excavated soil into the bentonite slurryexcavated soil into the bentonite slurry• The boring is guided by the guide wallsThe boring is guided by the guide walls• Dimensions range from (2.1*0.6) to Dimensions range from (2.1*0.6) to

(2.1*2.1)m(2.1*2.1)m

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The HydrofraiseThe Hydrofraise

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The HydrofraiseThe Hydrofraise

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The De-sanderThe De-sander• The de-sander separates the excavated The de-sander separates the excavated

soil from the bentonite slurry soil from the bentonite slurry• The slurry fit for recirculation is The slurry fit for recirculation is

reused, the polluted slurry is stored in reused, the polluted slurry is stored in the dumping silosthe dumping silos

• Excavation product is separated to be Excavation product is separated to be carried away on dump truckscarried away on dump trucks

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The De-sanderThe De-sander

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The De-sanderThe De-sander

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Another System:

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The Process:

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• Construction of Guide WallsConstruction of Guide Walls• Bore the primary wallsBore the primary walls• Dropping the Steel CageDropping the Steel Cage• Pouring the Primary WallsPouring the Primary Walls• Repeat with Secondary WallsRepeat with Secondary Walls

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Construction of Guide WallsConstruction of Guide Walls

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Diaphragm Wall Construction

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P-7

P-1P-3

P-5

P-9

P-11

P-13

S-8

S-2

S-4

S-6

S-10

S-12

S-14

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P-7

P-1P-3

P-5

P-9P-11

P-13

S-8

S-2S-4

S-6

S-10S-12

S-14

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Injection (Plugging)• To overcome the GWT problem, a To overcome the GWT problem, a

grout/gel plug should be injected to grout/gel plug should be injected to seal the bottom before excavation seal the bottom before excavation and dewatering startsand dewatering starts

• The plug can be permanent (grout)The plug can be permanent (grout)• Or temporary (gel) until the raft level Or temporary (gel) until the raft level

is reached, then a permanent raft is is reached, then a permanent raft is constructedconstructed

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Excavation and Dewatering• After the construction domain is After the construction domain is

sealed, excavation can start for the sealed, excavation can start for the remaining activities to proceedremaining activities to proceed

• During the excavation, the water During the excavation, the water must be drainedmust be drained

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Injection Excavation and Dewatering

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Slabs

• The final stage in finishing the The final stage in finishing the ventilator is casting the slabs.ventilator is casting the slabs.

• Slabs are cast from top to bottom Slabs are cast from top to bottom unlike the usual sequence.unlike the usual sequence.

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Slabs• Locations of the slabs are determined Locations of the slabs are determined

before the reinforcement cage is before the reinforcement cage is prepared.prepared.

• Slab reinforcement is placed in the cage Slab reinforcement is placed in the cage and ended with the mechanical spliceand ended with the mechanical splice

• The mechanical splices are protected The mechanical splices are protected from the concrete using foamfrom the concrete using foam

• When casting the slab, the splices are When casting the slab, the splices are located and exposed to be connected to located and exposed to be connected to the diaphragm wall.the diaphragm wall.

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Slabs

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Slabs

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Slabs• And then the steel is connected via And then the steel is connected via

the mechanical splice.the mechanical splice.• Concrete is cast.Concrete is cast.• A vertical shaft is made to allow A vertical shaft is made to allow

working in the lower floorsworking in the lower floors

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Slabs• The level under construction is The level under construction is

accessed using the floors cast aboveaccessed using the floors cast above• Pouring and excavation equipment Pouring and excavation equipment

are kept on the ground level.are kept on the ground level.• Access to the floor under Access to the floor under

construction is through the working construction is through the working shaftshaft

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