Stability Analysis of Antidip Bedding Rock Slopes with Very Low-Persistent Cross Joints Using a Limit-Equilibrium Model and Fracture Mechanics

Abstract

Antidip bedding rock slopes always contain a developed set of joints that dip into the free surface; however, sometimes they have some gently inclined cross joints, and the persistence ratio (k) of these cross joints exerts important influences on the stability and failure modes. In this work, a limit-equilibrium model combined with a fracture mechanics (FM) method was established to predict the stability of antidip bedding rock slopes with very low-persistent cross joints. Rock layers that might undergo toppling failure were analyzed with the theories of Mode I fracture in FM; layers with the potential for shear–sliding failure were studied by solid mechanics and theories for Mode II fracture from FM. Then, a practical slope and a model test (reported in previous studies) were used to verify the feasibility of the proposed method. The calculated results were consistent with the actual state of the slope and the experimental result, which indicated that a limit-equilibrium model combined with an FM method could be used to predict the stability of such slopes. To further approve the rationality of the method, a contrastive analysis was conducted that used two other methods. The results showed that the predicted factors of safety (FS) of the proposed method were conservative and on the safe side. The proposed method could be used by engineers to evaluate and design such rock slopes.