The effect of geometrical parameters on wedge failure of rock slopes using physical and numerical modelling

Abstract

This study investigated the role of the geometrical parameters of a wedge block on its stability using physical and numerical modeling. For the purpose of physical modeling, a new experimental setup was developed, and the stability of rock slopes was modeled. Sensitivity analysis was performed on four geometrical parameters: tilt angle of the wedge (β), included angle of the wedge (ξ), the apparent dip of the slope in the sliding direction (Ψ_fi), and the difference in dip direction of the slope face and discontinuities intersection line (Δα). A total number of 89 rock slope models were tested, and the wedge factor (K) was calculated for each model. Subsequently, 3D numerical models, corresponding to each physical model were conducted. Rock slope face inclination was applied by defining gravity vectors in different directions, which led to the development of models with a much simpler geometry. Ultimately, numerical modeling results almost align with the outcomes of physical modeling. Good agreement was observed between physical and numerical models and the existing analysis. According to the results, the behavior of the wedge-shaped block and its safety factor depends on the geometric conditions of the wedge and its slope, regardless of the rock material properties, as models were tested with two different materials. Additionally, sensitivity analysis demonstrates that by increasing Δα, the slope safety factor was increased, as expected. Finally, practical graphs were developed by which the safety factor against the wedge failure can be estimated using the geometrical parameters of the wedge and the rock slope.