Predicting permanent slope displacements due to multidirectional earthquake shaking from unidirectional shaking analyses

Abstract

The current state-of-practice for time-domain modelling of seismic slope stability is to apply a single horizontal ground motion component in the downslope direction. However, several numerical and experimental studies have demonstrated the importance of multidirectional shaking on seismically induced permanent displacements. To understand better the effect of multidirectional shaking on seismically induced permanent slope displacements, we performed 28,100 three-dimensional finite element slope stability analyses using 230 ground motion record pairs, 48 soil profiles, and four different combinations of ground motion components. We then performed traditional regression analyses and applied machine learning techniques to develop simplified models that estimate the permanent displacements due to multidirectional shaking from the results of analyses where only one component of the ground motion is applied downslope. The simplified model has R2 = 0.91 and uses the displacement from a unidirectional shaking analysis as its only input variable. The standard deviation decreases as the predicted unidirectional shaking displacements increase.