Determination of critical slip surface in slope analysis

A new method of finding the critical slip surface in slope stability analysis is developed in this paper, based on the limit equilibrium technique with added stress acceptability criterion. The stress acceptability criterion is based on the limited strength of soil. The slip surface is developed in terms of the critical acceleration. The procedure uses stress acceptability as a prerequisite to derive a system of non-linear equations to determine the slip surface slice by slice upwards; no prior assumption of the shape of the surface is needed. This surface simultaneously satisfies the kinematical acceptability criterion. The whole procedure includes both homogeneous and non-homogeneous slopes. In terms of the minimum factor of safety, the obtained critical slip surfaces compare well with those obtained through methods based on optimisation techniques. In addition, the solution provides information on the critical acceleration and the kinematically acceptable interslice boundaries for the analysis of seismic displacements of slopes using a multi-block sliding model.