Three-dimensional base stability of rectangular excavations in soft soils using FEM

Abstract The three-dimensional base stability of rectangular excavations in soft soils was evaluated using the finite element method with reduced shear strength. Numerical results indicate that the base stability of excavations was significantly influenced by the following factors: (1) the depth to width ratio, (2) the thickness of the soft soil layer between the excavation base and the hard stratum, (3) the depth of walls inserted below the excavation base, (4) the stiffness of walls, and (5) the length to width ratio of the excavation. The three-dimensional effect can be neglected at the length to width ratio larger than six. Terzaghi's equation for base stability can be used to evaluate the three-dimensional base stability of rectangular excavations after modification.

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