Probabilistic solution for the seismic sliding displacement of slopes in Greater Vancouver

Abstract

Greater Vancouver has the highest seismic risk in Canada with significant potential to cause earthquake-induced hazards including seismic slope failures. The available methods to predict seismic slope failures in practice are using seismic displacement prediction models (SDPMs) based on Newmark sliding displacement analogy. Seismically induced permanent displacements are calculated using earthquake hazard parameters and soil strength parameters represented by yield acceleration of the slope (ky). The primary source of uncertainty in assessing the likely performance of a slope during an earthquake is the input ground motion parameters along with the uncertainties associated with various SDPMs available. Considering the seismicity sources in Greater Vancouver and the latest updates in SDPMs, in this paper a probabilistic solution for the seismic sliding displacement of slopes for the region is presented. The uncertainties in input seismic parameters and SDPMs are both taken into account and probabilistic displacements are determined for different values of ky. Displacement seismic hazard curves are an output from the probabilistic evaluation of the problem, which are additionally presented as uniform displacement hazard spectrum (UDHS) for a 2% probability of exceedance in 50 years hazard level. The current procedure for seismic slope evaluation in Greater Vancouver is reviewed and critiqued with an illustrative example and the alternative probabilistic method is recommended for engineering practice.