Probabilistic Seismic-Stability Analysis of Slopes Considering the Coupling Effect of Random Ground Motions and Spatially-Variable Soil Properties

A probabilistic slope stability analysis framework based on the Newmark permanent displacement method and probability density evolution theory is presented to quantify the coupling impact and propagation of combined uncertainties of random ground motions and spatially variable soil properties simultaneously. The effect of random fields on static stability of the slope was first investigated to select appropriate random field parameters to ensure the initial static stability for permanent displacement analysis. Then, the generated stochastic ground motions and discretized cross-correlated non-Gaussian random fields of soil properties were assigned to the finite-element model of the slope to determine the stochastic seismic responses of the slope. The stochastic deformation results from the combined uncertainties (randomness of ground motion and soil spatial variability) and single uncertainty (only randomness of ground motion) were also compared to demonstrate that neglecting spatial variability will lead to overestimation of slope safety. The dynamic reliability results of the slope under various seismic intensity levels were finally used to construct seismic fragility curves of three different hazard levels of the slope.