Basal Stability Analysis of Braced Excavations with Embedded Walls in Non-homogeneous Clay by a Kinematic Approach

The embedded wall has beneficial effects on the basal stability of braced excavation in clay. This paper investigates the basal stability of excavations with wall embedment in undrained clay using the kinematic approach of limit analysis, with the consideration of non-homogeneous undrained shear strength of clay. The proposed failure mechanism consists of three rigid blocks and one shear zone, and the least upper bound solutions and the corresponding critical failure mechanisms are obtained through optimization with respect to the geometric parameters. Comparison of the factor of safety from the proposed method with the limit equilibrium predictions based on the modified Terzaghi method was performed. Parameter study showed that the basal stability of excavations is significantly influenced by the wall embedment and the non-homogeneous strength of clay. Finally, the proposed mechanism was validated by five field excavation cases near or at failure and a numerical excavation case. The results show that the proposed method could reasonably describe the actual stability of excavations in both homogeneous and non-homogeneous clay.