Seismic Slope Stability

The performance of soil slope during an earthquake is generally analyzed by three different approaches which are pseudo-static methods, Newmark’s Sliding Block method and numerical techniques. In pseudo-static approach, the effects of an earthquake are represented by constant vertical (kv) and horizontal (kh) seismic acceleration coefficients and the factor of safety is evaluated by using limit equilibrium or limit analysis or finite element method of analysis. Newmark’s sliding block method evaluates the expected displacement of slope subjected to any ground motion obtained from the integration of the equation of motion for a rigid block sliding in an inclined plane. Numerical methods determine the expected displacements obtained from the stress ? strain relationship of a soil mass. In this paper the stability of a model soil slope, comprising of an embankment with two canal bunds at the top, at different stages of construction, i.e. only embankment, embankment with empty canal bunds and embankment with canal bunds filled with water, with different foundation soils in different seismic zones have been analyzed and results have been plotted in the form of variation of factor of safety with horizontal seismic acceleration coefficient (kh). The critical case has been further analyzed under dynamic conditions. Dynamic analyses have been carried out by plotting the response spectrum curve and selecting 2001 Bhuj earthquake motion as the typical ground motion.