UNIFIED FORMULATION FOR ANALYSIS OF SLOPES WITH GENERAL SLIP SURFACE

The general availability of computers has provided efficient means of assessing the stability of slopes using several analytical methods. Ho wever, the increased use of computers coupled with a lack of unified p resentation of the various methods sometimes leads to conflicting resu lts. It is shown that the current analytical methods can be grouped in to three categories based on the hypotheses used to describe the inter nal forces, namely: (1) The direction of the internal forces: (2) the height of the line of thrust; and (3) the shape of the distribution fu nction of the internal shear forces. An analytical framework incorpora ting this idea is presented to facilitate and unify slope stability an alysis with general slip surfaces. The study is a generalization of ea rlier work performed by Espinoza et al. for circular slip surfaces. Th e framework incorporates most current methods of analysis. The analyti cal model is implemented in a computer program. The program was used t o study several case examples. On this basis, key issues associated wi th the influence of the internal shear forces on the factor of safety, for both circular and general slip failure surfaces, are discussed. I t appears that for circular failure surfaces, even with heterogeneous soil stratigraphy the factor of safety is not affected by the choice o f a particular hypothesis. On the contrary, for general slip surfaces this choice may significantly affect the results.