Seepage on local stability of slurry trench in deep excavation of diaphragm wall construction: Fid-Bau Portal

Seepage on local stability of slurry trench in deep excavation of diaphragm wall construction

Liu, Wei / Shi, Peixin / Cai, Guoqing / Cao, Chengyong

Abstract The stability of slurry trench is of importance in diaphragm wall construction. The local stability of slurry trench under seepage application is investigated in this research. In the current research, the local instability of slurry trench is identified as the soil collapse in an instable sublayer and a three-dimensional translational failure mechanism is developed. In this mechanism, the local stability is initialed by the movement of a single rigid block and the seepage application is accounted by introducing the analytical model of semi-confined seepage. The stability is analyzed through kinematic approach and the upper bound solution of safety factor is deduced as a result. The stability is evaluated by optimizing the mechanism for the local failure. Using the current solution, the seepage effect on the stability is analyzed. Regardless of seepage, the stability is mainly dependent on the shear strength of the sublayer. Under seepage application, the failure zone is enlarged and the safety factor decreases as a result. The effect of seepage on the stability is significantly influenced by piezometric head difference $Δ p$ and leakage ratio $λ$ of the sublayer. The validity of the current solution is examined by investigating the case of diaphragm wall installation in Suzhou, China.