A diaphragm wall is a reinforced concrete wall that is cast in-situ. The trench is prevented from collapsing during excavation by the use of bentonite slurry. The bentonite slurry forms a thick deposit (the cake) on the trench wall which balances the inward hydraulic forces and prevents ground water flows into the trench.
Diaphragm walls provide rigid, cost effective solutions for deep permanent retaining walls and shafts.
Coventional cable grab or hydraulic grab is used for soft to hard subsoil conditions, while trench cutter is used for very hard subsoils or rock formations.