Diaphragm walls are concrete or reinforced concrete walls constructed in slurry- supported, open trenches below existing ground. Concrete is placed using the tremie installation method or by installing precast concrete panels (known as a precast diaphragm wall). They can be constructed to depths of 100 meters and to widths of 0.40 to 1.50 meters.
Diaphragm wall construction methods are relatively quiet and cause little or no vibration. Therefore, they are especially suitable for civil engineering projects in densely populated inner city areas. Due to their ability to keep deformation low and provide low water permeability, diaphragm walls are also used to retain excavation pits in the direct vicinity of existing structures. If there is a deep excavation pit at the edge of an existing excavation, only small amounts of residual water will penetrate.