Generalised framework of limit equilibrium methods for slope stability analysis

A generalised framework is proposed in this paper incorporating almost all of the existing limit equilibrium methods of slices for slope stability analysis with general slip surfaces. The force and moment equilibrium equations are derived in terms of the factor of safety and the initially assumed normal stress distribution over the slip surface, multiplied by a modification function involving two auxiliary unknowns. These equations are then analytically solved to yield explicit expressions for the factor of safety. Various assumptions regarding the interslice forces can be transformed into a unified form of expression for the normal stress distribution along the slip surface. An iterative procedure is developed to expedite the convergence of the solution for the factor of safety. Experience to date indicates that the process generally converges within a few iterations. Computation schemes are suggested to avoid numerical difficulty, especially in computing the factor of safety associated with the rigorous Janbu method. The present framework can be readily implemented in a computer program, giving solutions of slope stability associated with a number of conventional methods of slices.