ABSTRACT
This chapter presents a method to back-calculate the strength parameters from the slip surface in a two-layer slope. Back analysis of slope failures has been a useful tool to determine soil strengths along the slip surface especially in connection with remedial stabilization works. Existing back analyses have been performed only for failed slopes in homogeneous soils. For a two-layer slope with a known geometry, unit weight and pore water pressure distribution, the position of critical slip surface from a limit equilibrium stability analysis will remain unique for a given set of values regardless of the magnitude of individual strength parameters of two soil layers. The proposed method satisfies the two essential requirements for back analysis: the actual failure surface must be consistent with a theoretical critical slip surface, and the factor of safety should be equal to unity.
