SLOPE SYSTEM RELIABILITY WITH GENERAL SLIP SURFACES

Abstract

The main requirements for assessing the system reliability of slopes are outlined briefly and a comprehensive procedure is presented based on potential slip surfaces of arbitrary shape. The evaluation of system reliability of soil structures such as slopes is important because of the spatial variability of geotechnical parameters within any soil layer and also the fact that slopes are frequently associated with multi-layered soil deposits. The performance function for the stability of a slope, defined in terms of a 'factor of safety', is usually inexplicit and non-linear. A 'rigorous' method of slope stability analysis such as the Generalised Procedure of Slices may be used as the basis of a reliability analysis. A complete analysis should include the search for a critical slip surface and the calculation of reliability index or the probability of failure associated with it. System reliability bounds are evaluated by considering the probabilities of failure associated with a number of slip surfaces including the critical slip surface. It is shown that the upper bound of the system failure probability can be significantly higher than the failure probability associated with the critical slip surface. This finding is significant for slope design and for geotechnical risk assessment generally.