Displacement-Based Seismic Stability Analyses of Reinforced and Unreinforced Slopes Using Planar Failure Surfaces

In the present study, the most simplified planer failure surface is assumed for the seismic stability analysis of soil slopes and the behaviors of this simple failure surface over the existing complex surfaces are studied. A model reinforced soil slope is divided into a number of finite horizontal slices for the seismic analysis using a limit equilibrium method (LEM) with pseudo-static approach. The variations of factor of safety with respect to horizontal seismic acceleration coefficient under different soil and seismic conditions are shown. It is found that for the slope angle β = 25⁰; angle of friction φ = 30⁰ and for the increase in the horizontal seismic acceleration coefficient k_h from 0.2 to 0.3, the respective decrease in the percentage of the factor of safety is about 21%. It is concluded that the stability of slope decreases with increase in both the horizontal and vertical seismic acceleration coefficients. The present results are compared with the available results in the literature. Also, the displacement of slope for different soil and seismic conditions and time of cycle of earthquake loading are evaluated. As expected, the displacement of the slope is found to increase significantly with increase in the seismic accelerations.