Efficient Reliability Sensitivity Analysis For Slope Stability In Spatially Variable Soils

Landslides caused by slope failure is one of the major hazards of geotechnical engineering in our country.Traditional deterministic slope stability analysis method can't accounts for the uncertainties in geotechnical parameters and calculation models.Comparatively speaking,the miscellaneous uncertainties is properly valued in the probabilistic slope stability analysis.Among those uncertainties,geotechnical spatial variability is the most unneglectable factor in the probabilistic slope stability analysis.Reliability sensitivity analysis provides a rational vehicle to shed light on effects of different uncertain parameters on slope failure probability when only a limited number of data is available.Because of simple theory and accurate calculation,direct Monte Carlo simulation(DMCS)has been one of the most widely-used reliability analysis methods in recent years.But using DMCS method for slope reliability sensitivity analysis needs to repeat the whole simulation process,especially in the case that failure probability of slope is very low,the disadvantage of low computational efficiency in slope reliability sensitivity analysis is more obvious.Considering the above problems,this paper develops a research on sensitivity analysis of single failure mode and system slope reliability considering soil spatial variability based on the slope stability analysis,the main conclusions in this paper are as follows:1 Limitations and applicability of existing probabilistic stability analysis method is discussed in the study of sensitivity reliability analysis considering soil spatial variability.Indicate that the key of sensitivity analysis of slope reliability considering soil spatial variability based on DMCS method is to improve the efficiency of sensitivity analysis,and to solve the high dimensional random variables in the random field model.2 An efficient reliability sensitivity analysis method is proposed based on DMCS and probability density re weighting method.Only one run of DMCS is needed in the proposed approach,avoiding repeated generation of random samples and performing slope stability analysis.This saves a large amount of computational efforts,and significantly improves computational efficiency for DMCS-based reliability sensitivity analysis.3 Local spatial averaging technique is applied to construct the joint probability density function of geotechnical parameters with relatively low dimensions to solve the problem of high-dimensional random variables in the efficient slope reliability sensitivity analysis method considering soil spatial variability.This paper provides a way to make the probability density reweighting method feasible in reliability sensitivity analysis of slope stability in spatially variable soils.4 According to the proposed method,the Efficient Slope Reliability Revised Analysis Software(WHUERAS)is developed which is based on the tools of EXCEL and Visual Basic for Applications.This software can not only customize the dominant performance functions of slope,but also invoke the widely-used stability analysis software such as GEO-SLOPE to solve the reliability sensitivity analysis problems of slope stability.5 Considering soil spatial variability,the proposed method can not only be applied to the reliability sensitivity analysis of single failure mode,but also to the system reliability sensitivity analysis.And the efficiency and accuracy of the proposed method is respectively verified by a design scenario of James Bay Dyke and the case of Lodalen Slope.