Effects of spatial variability of weak layer and seismic randomness on rock slope stability and reliability analysis

Rock slope stability is a key research issue in geotechnical engineering. Weak layer is a distinct feature distinguishing the rock slopes from soil types, and its existence considerably controls the slope stability. Taking in to account the differences in mineral composition, sedimentary conditions, stress history and other geological processes, the physical and mechanical parameters of rock mass generally show certain spatial variability. On the other hand, for slope failures such as landslides, rockfall and debris flows, earthquake is one of the main triggering factors. In this paper, an efficient framework is presented to evaluate the stability of the rock slope with weak layers considering spatial variability of rock mass strength properties under seismic loading. A rock slope model with weak layer is established, followed by modeling of both the spatial variability of cohesion (c) as well as friction angle (phi) of rock material and weak layer characterized by random field method. Random seismic loading is applied via the pseudo-static method. The Latin Hypercube Sampling (LHS) is adopted to calculate the failure probability of rock slope. The results indicate that the spatial variability of weak layer has more influence on the slope stability than that of rock material, and the influence of seismic randomness cannot be neglected. In addition, under different seismic loadings, the spatial variability of weak layers and seismic randomness have different effects on slope failure probability.