Reliability Analysis of a Finite Slope Considering the Effects of Soil Uncertainty

摘要

Soil uncertainty plays a crucial role in the analysis and design of any geotechnical structure. Reliability based probabilistic method of analysis is particularly suitable to address the situation arising due to soil uncertainties. This paper presents a reliability based probabilistic method of analysis of a finite slope by considering the uncertainty in the cohesion and angle of internal friction of the soil. The reliability index (β) and its corresponding probability of failure (P_f) of the slope are determined using different methods namely Monte-Carlo simulation (MCS) method, First order second moment (FOSM) method and Subset simulation (SS) method. The reliability based probabilistic slope stability analysis has been developed and carried out in a MS-Excel spreadsheet. This spreadsheet mainly analyzes three different models i.e. deterministic model for calculating the factor of safety of the slope, uncertainty model for generating random samples of uncertain parameter of the soil and uncertainty propagation using subset simulation. The stability analysis is carried out using the ordinary method of slices. It is found that the SS method has shown better performance in terms of efficiency and accuracy as compared to the MCS method and FOSM method. Moreover, the study also demonstrate that the SS method can help in understanding the problem and can better assess the risk involved.