Three-Dimensional Slope Stability Under Tri-directional Pseudo-Static Seismic Loading

In reality, the constitutive materials of natural slope are quite heterogeneous. The materials are assumed as homogeneous, isotropic, and uniformly distributed in horizontal direction for a two-dimensional analysis of slope, which is an oversimplification of an actual case. However, a three-dimensional analysis for slope is preferred in such case where slopes have complex geometry including sharp ridges, corners, cut and fill slopes, unplanned excavations, heterogeneous constitutive materials (varying along depth and along out of plane direction) and slopes subjected to seepage and seismic loadings. In this article, a numerical study has been conducted to obtain the FOS of four generic three-dimensional slopes. Finite element analyses have been performed for three-dimensional slopes using the proprietary software ABAQUS following the strength reduction method. The seismic loads have been applied in simplified pseudo-static form in three mutually perpendicular directions to estimate the FOS of 3D slopes having complex geometry. A parametric study has been carried out on four slopes having same cross section, soil property, and boundary conditions with varying geometries to understand the variation in FOS and failure surface with changing complex geometry. It was apparent that on increasing the seismic coefficients, FOS kept on reducing.