Search Algorithm for Minimum Reliability Index of Earth Slopes

Abstract

In probabilistic slope stability analysis, the similarity and differences of the surface of minimum factor of safety (FS) and the surface of minimum reliability index (β) have not been investigated fully. Probabilistic analyses have often been performed on the surface of minimum FS, and sometimes on an arbitrary surface. The surface of minimum FS and the surface of minimum β do not generally coincide. In this paper, an expedient technique is presented to search for the critical probabilistic surface utilizing existing deterministic slope stability programs. This technique is based on searching the critical surfaces obtained using specific combinations of soil parameter values. The critical probabilistic surface was found to generally coincide with that obtained by setting one dominant parameter to a low value. The technique is examined by a parametric study and applied to some case studies. It proved to provide a practical and efficient method to locate the critical probabilistic surface.