Coupled effects in stability analysis of pile-slope systems

A numerical comparison of predictions by limit equilibrium analysis and 3D numerical analysis is presented for a slope-pile system. Special attention is given to the coupled analysis based on the explicit-finite-difference code, FLAC 3D. To this end, an internal routine (FISH) was developed to calculate a factor of safety for a pile-reinforced slope according to a shear strength reduction technique. Coupled analyses were performed for stabilizing piles in a slope, in which the pile response and slope stability are considered simultaneously and subsequently the factors of safety are compared to a solution for a homogeneous slope using an uncoupled analysis (limit equilibrium analysis). Based on a limited parametric study, it is shown that the factor of safety for the slope is less conservative for a coupled analysis than for an uncoupled analysis and thus represents a definitely larger safety factor when the piles are installed in the middle of the slopes and the pile heads are restrained.