Reliability-Based Assessment of Slopes Stability Considering Seismic and Soil Uncertainty

Abstract

In slope instability hazard assessment, it is essential to account for uncertainties associated with both soil heterogeneity (the mechanical and physical properties of the soil) and environmental conditions, such as hydraulic boundary conditions, external loads, and seismic actions. This study investigates the reliability of slope stability by integrating both the intrinsic and spatial variability of soil properties together with hydro-mechanical and seismic loading effects. Two representative case studies are analysed: a natural slope and a zoned earth dam. A combined deterministic–probabilistic framework is employed, in which the Bishop limit equilibrium method is used to calculate the factor of safety, while probabilistic methods including Monte Carlo simulation, the First-Order Reliability Method (FORM), and random field modeling, are applied to estimate the probability of failure. Sensitivity analyses are also conducted to identify the most influential parameters affecting slope stability. The results indicate that groundwater level rise, seismic acceleration, and soil heterogeneity significantly increase the probability of failure. Further more, kriging-based random field models demonstrate that spatial variability of soil shear strength parameters has a decisive effect on reliability estimates. The study demonstrates that neglecting either spatial variability or seismic loading leads to a misleading stability assessment, particularly for slopes and earth dams subjected to unfavourable hydrogeological conditions.