Diaphragm walls are very rigid walls offering significant resistance to bending from lateral loads as well as being very water resistant.

Common uses

Slope stabilization
Support of open or top down excavations
Create barriers to groundwater flow
Permanent retaining walls

Process

Diaphragm walls refers specifically to a slurry wall built for some type of structural support. Since most diaphragm walls are usually thick (>2.5 feet) and built of reinforced concrete, they are very rigid walls offering significant resistance to bending from lateral loads as well as being very water resistant. Diaphragm walls are ideal for lateral earth support for deep excavations and are often incorporated as the permanent building basement walls. This creates additional savings for the project by eliminating the need for temporary earth support and extensive dewatering.

Since reinforced walls are designed and constructed as a series of panels, there is no practical limit to their overall length. Individual panels usually range in sizes between 15 to 30 feet in length, with standard widths ranging between 24, 30, 36 and 48 inches. Depths of the wall have exceeded 200 feet regularly. Possible shapes of walls, depending on the purpose of the wall, include right angles, polygonal, T-shaped and cross-shaped walls.

Clam Shells (Cable Grabs) 

This equipment is suitable for soft, medium dense to dense soil & boulders (in combination with chisels), to suggested depths of up to 120ft (37m).

Hydraulic Clam Shells (Hydraulic Grabs) 

This equipment is suitable for hard soil and stiff clays, to suggested depths of up to 260ft (80m).

Hydromills (Cutters)

This equipment is suitable for nearly all soils and rock types. Hydromills can use different types of cutting wheels depending on the soil and rock conditions. Achieving large depths is possible (>500ft (150m)), while maintaining very accurate verticality (<.3%) which is essential for proper closure at depths of hundreds of feet.

The application of the hydromill technique for the construction of large projects with deep slurry walls and cut-off walls offers the following advantages over the conventional clamshell techniques: economy, output, reliability, environmental compatibility.

The hydromill continuously removes soil from the bottom of the trench, breaks it up, and mixes it with the bentonite slurry in the trench.  The slurry, heavy with soil particles, is pumped through pipes to the desanding plant where it is cleaned and returned to the trench.

Advantages

Can be installed close to existing structures and in restricted headroom
Can be used in conjuction with top down construction

Quality assurance

Keller has a fleet of specialist wall excavation and construction equipment to complete all types of diaphragm walls.