Simplified approach for locating the critical probabilistic slip surface in limit equilibrium analysis

Abstract. This paper aims to develop a rapid and practical procedure that can locate the slip surface for a slope with the minimum reliability index for limit equilibrium analysis at the minimum expense of time. The comparative study on the reliability indices from different sample numbers using the Monte Carlo simulation method has demonstrated that the results from a large enough sample number are related to those from a small sample number with high correlation indices. This observation has been tested for many homogeneous and heterogeneous slopes under various conditions in parametric studies. Based on this observation, the reliability index for a potential slip surface can be calculated with a small sample number, and the search for the minimum reliability index and the slip surface can be determined by a heuristic optimization algorithm. Based on the comparisons between the critical deterministic and probabilistic slip surfaces for many different cases, the use of the proposed fast method in locating the critical probabilistic slip surface is found to perform well, which is suitable for normal routine analysis and design works.