Quasi-static stability analysis of homogeneous soil slopes under effect of surcharge and earthquake

The effects of surcharge and pseudo-static seismic forces on soil slopes were investigated by applying the kinematical approach of limit analysis theory and strength reduction technique. The rotational failure surface was considered and analytical expressions is derived to calculate the safety factor of slope subjected to surcharge and earthquake loading. The upper bound solutions for analytical expression are presented by applying iterative optimization method. From the comparative analysis, it can be seen that the solutions presented here agree well with available predictions both in simple static state and dynamic state. Parametric analysis shows that the safety factor of slopes decreases nonlinearly as the stability condition of a slope deteriorates when an increase in values of slope angle, surcharge and pseudo-static seismic forces occurs. From the numerical results, it also can be seen that latent slide surface moves inward to the slope with the increase of surcharge q and horizontal effect kh and the decrease of vertical effect kv, sliding surface and failure mass becomes bigger. The effect of vertical seismic acceleration on the stability of reinforcement slopes is significant especially for strong motion earthquake; i.e. that the effect of the vertical seismic acceleration should be taken into account in the engineering practices.