Probabilistic Assessment Of Slope Seismic Stability Consideririg Multiple Uncertain Sources

China is a mountainous country with frequent earthquakes.The assessment of slope stability under earthquakes is an important issue in the design of slope engineering in the earthquake-prone area.Based on the demand of seismic stability assessment of a rock slope in a nuclear power plant,this paper studied the probabilistic evaluation of slope seismic stability considering multiple uncertain sources that come from the earthquake-induced ground motion and the intrinsic variability of geotechnical parameters.The methods proposed in the paper are of great significance in both theoretical research and practical engineering application.The main contents of this paper are as follows:(1)The existing deterministic and probabilistic methods were extensively reviewed.The research progresses of slope seismic stability have been summarized,and the shortcomings in the existing slope seismic stability evaluation methods have been commented.(2)Based on the stochastic ground motion simulation method and the permanent displacement analysis,a probabilistic evaluation methodology using Monte-Carlo simulation is proposed to assess the slope seismic stability which fully considers the uncertainties involved in both the earthquake and the slope parameters.(3)Then,the above-mentioned procedure was used for the seismic stability probabilistic evaluation of a rock slope in a nuclear power plant under diffferent scenarios.The shear wave velocity data of the site,the seismic fault information,the magnitude and the source-to-site distance of earthquake and the variability of the slope geotechnical parameters were considered in the analyses.The influence of site characteristics and seismic parameters on the obtained probabilistic results were discussed.The influence of variability of slope geotechnical parameters on the failure probability of the slope were also investigated.Therefore,the different effects of different uncertainty sources,i.e.,the uncertainties from the earthquake and the slope geotechnical parameters,were systematically studied.(4)Based on the quasi-static method and first-order reliability method,the reliability method of slope seismic stability is proposed.The reliability indexes and the corresponding probabilities of failure of the rock slope under different seismic conditions were calculated.The influence of seismic parameters and the variability of the geotechnical strength parameters on the slope seismic stability were discussed.The obtained results of reliability-based method were compared with the results of the fully probabilistic analysis method that based on the stochastic ground motion simulation and the permanent displacement analysis.The conclusions of the paper are summarized as below:(1)A fully probabilistic assessment method for seismic stability of slopes considering the uncertainty involved in both earthquake and slope geotechnical parameters is proposed.(2)A reliability method for slope seismic stability assessment based on first-order reliability method and the quasi-static method is proposed.(3)Under the framework of the above-mentioned two methods to assess slope seismic stability considering multiple uncertain sources,the influences of different parameters,including the seismic intensity,the epicentral distance of earthquake and the variability of geotechnical parameters,etc.,on a rock slope seismic stability were investigated in detail.The obtained results of the two proposed methods are consistent with the observed and statistical results from post-disaster investigation of typical earthquake landslides,which indicates the reliability and applicability of the methods proposed in the paper.