Stability Analysis of L-Shape Slurry Trench During Concrete Diaphragm Wall Installation in $$ c-\varphi $$c-φ Soils

In the concrete diaphragm wall (CDW) construction, the L-shaped diaphragm wall is used to form an enclosed retaining structure. Due to the complicated stress change in trenching, the L-shaped trench has the lower stability than the regular rectangular trench. This paper investigates the trench instability during the L-shape slurry trench excavation based on the upper bound analysis. A 3D kinematically admissible mechanism defining the failure for the L-shaped trench is constructed. The safety factor on the trench and corresponding failure pattern are obtained through the upper bound analysis. The influence of trench geometries and the soil properties on the trench stability are discussed by the parameter analysis.