Concrete Diaphragm Walls: Construction, Design, and Applications

Diaphragm walls are a structural element commonly used in civil engineering projects. They are vertical concrete walls constructed underground to support and stabilise the surrounding soil and structures. This blog post will discuss concrete diaphragm walls, their design, construction, and applications.

What are Concrete Diaphragm Walls?

Concrete diaphragm walls are a type of underground wall constructed using reinforced concrete to provide structural support and prevent water from infiltrating the surrounding soil. They are typically used to build deep underground structures, such as tunnels, dams, and underground car parks. Concrete diaphragm walls can be constructed in varying thicknesses and depths, depending on the project's needs.

Design of Concrete Diaphragm Walls

The design of concrete diaphragm walls depends on several factors, including the depth of the wall, the type of soil surrounding the wall, the water table, and the loads it will be subjected. Typically, the thickness of the wall ranges from 50 cm to 150 cm, with the reinforcement bars placed in a specific configuration.

One important factor to consider in the design of concrete diaphragm walls is the type of reinforcement used. The reinforcement can be in the form of steel bars, welded mesh, or fibers. The spacing and diameter of the reinforcement bars also play a crucial role in ensuring the wall's structural integrity.

Construction of Concrete Diaphragm Walls

The construction of concrete diaphragm walls involves several steps, including:

1. Excavation: A trench is excavated using a specialised trench cutter or hydraulic clamshell grab.

2. Reinforcement Placement: Steel reinforcement bars are placed in the trench according to the design specifications.

3. Concrete Pouring: The trench is filled with concrete using a tremie pipe, which ensures that the concrete is of high quality and free from voids.

4. Panel Jointing: After the concrete has been set, the individual panels of the diaphragm wall are joined together using various methods, including dowels or post-tensioning.

Applications of Concrete Diaphragm Walls

Concrete diaphragm walls are commonly used in civil engineering projects requiring underground structures. They are instrumental in building deep basements, underground tunnels, underground car parks, and dams.

In deep basements, concrete diaphragm walls support the surrounding soil and prevent water from infiltrating the structure. In the construction of underground tunnels, they provide stability to the surrounding soil and avoid tunnel collapse.

Concrete diaphragm walls are also used in the construction of underground car parks. They are beneficial in locations where the water table is high and water infiltration is a concern. By providing a waterproof barrier, concrete diaphragm walls can prevent water from infiltrating the underground car park and causing damage to vehicles.

In the construction of dams, concrete diaphragm walls are used to prevent water from seeping into the dam's foundation. They provide lateral support to the dam structure and help evenly distribute the water's weight and other loads.

Conclusion

Concrete diaphragm walls are essential to many civil engineering projects, providing stability, support, and waterproofing to underground structures. The design and construction of concrete diaphragm walls require careful consideration of several factors, including the depth of the wall, the type of soil, the water table, and the loads it will be subjected. By providing a waterproof barrier and lateral support, concrete diaphragm walls play a crucial role in ensuring the safety and durability of underground structures.