Wedge stability analysis in fractured soft rock slopes for different orientations of seismic components

Abstract

Purpose. This paper focuses on the case of a rock slope in the Ouarzazate region in order to conduct a sensitive analysis to study the influence of seismic action orientations on wedge stability. Methods. To examine the wedge stability, a probabilistic approach related to the Monte Carlo method has been used. Firstly, the characteristics of joint families: orientations and fillings are analysed. Then, the influence of the seismic action on the rock slope stability for the most sensitive plunges is studied using the equations developed by J. Bray (1981). These equations make it possible to ultimately determine the safety factor for predicting the stability of the wedge. Findings. In this study, the ranges of values of the seismic action orientations leading to the rock wedge failure have been identified. Especially around the 284° trend, the minimum of the safety factor values have been obtain for different analyzed plunges. This means that the occurrence of an earthquake oriented at 284° and lateral to the slope disposition, oriented at 260°, gives rise to a risk of a slope failure. Originality. This study of rock slope stability made it possible to find the minimum safety factor values depending on the orientation of the seismic action by examining its sensitivity to all possible orientations: combinations of plunges and trends. Practical implications. This analysis makes it possible to find, whatever the orientation of the seismic action, the safety factor corresponding to the stability of the rock slope. Thus, a decision can be made on the appropriate reinforcement to ensure the rock slope stability, taking into account the case of the most unfavourable seismic action orientation found in this analysis.