Diaphragm WallPresented by

Thananchayan

Diaphragm Wall Diaphragm wall is generally reinforced concrete wall

constructed in the ground using under slurry technique.

The slurry forms a thick deposit on the wall of the trench which balances the inward hydraulic forces & prevents water flow into the trench.

Thickness of the wall can be between 300mm to 1500mm.

Depth of the wall can go up to 50m.

Diaphragm Wall Application Commonly used in congested areas.

Can be installed in close proximity to existing structure.

Practically suited for deep basements.

General Procedure of Construction

1. The excavation is carried out using a heavy self guidedmechanical grab suspended from a large crawler crane.

2. The diaphragm walls were excavated and constructed indiscrete panels of between 2.8m and 7.0m lengths.

3. As the excavation proceeds, support fluid was added into theexcavation to maintain the stability of the surrounding groundand to prevent a collapse. This fluid is called “Bentonite” or“slurry”, which is a poser made of a special type of soluble clayand is mixed at the mixing plant with potable water.

4. When the excavation is completed, the reinforcement cagewill be lowered and the concrete procedure will begin.

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Types of Diaphragm Walls

Structural Diaphragm walls: they are used as retaining walls for the perimeter walls of deep basements and underground parking facilities and subways.

Load bearing walls: they are used in place of drilled piers in foundation of tall buildings, bridge and piers.

Cutoff walls: in hydraulic structures diaphragm walls are used as impermeable cutoffs to prevent seepage below earth dams and weirs.

Cut & cover Tunnel

Cut off Wall

Under ground water tanks

Advantages of Diaphragm Wall

Suitable for unstable soil profiles below water table.

Limited construction time.

Where deeper than normal cantilever support may needed.

Designable to carry vertical loads.

Construction time of basement can be lower.

Minimize the settlement of adjacent building.

Cont.

Provides strong & water tight walls.

No vibration during installation.

Noise level limits to engine noise only.

Can be used for seepage control in dams.

Disadvantages

Not economical for small & shallow basements.

Require special equipment.

Questions & Clarifications?

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