Conventional calculations of seismic stability and permanent displacement of rock slopes are formulated assuming the soils obeying a linear Mohr–Coulomb yield criterion. However, experimental evidences show that the strength envelopes of almost all geomaterials are nonlinear in nature over a wide range of normal stresses and the influence of the intermediate principal stress is distinct. In this paper, the strength envelope of rock is considered to follow a nonlinear yield criterion and the Unified Strength Theory is introduced. A new methodology for evaluating seismic safety factor and permanent displacement of rock slopes is proposed according to the characteristic of joint rock. In this proposed method, the strength difference and tensile failure can be considered. The influences of angle of bedding slope, inclination of joint, unified strength parameter, tensile depth and seismic load are investigated. The results reveal that, with the increase of intermediate principal stress effect, the safety factor also increases. Obviously, the potential strength of filling materials is sufficiently developed under the guidance of the unified strength theory.
Predicting the stability of the rock slopes has always been a challenging problem for civil and mining engineers while dealing with dams, roads, tunnels, opencast mines, etc. The performance of rock slopes subjected to seismic action can be evaluated through seismic coefficient of safety and permanent displacement. The majority of existing methods depending on the fundamental approach adopted in each method fall into three categories: finite element methods (FEM), force based pseudo-static methods, and displacement-based sliding block methods (Cai, 1996). The FEM is one of the most comprehensive approaches to implement a through analysis of performance of soil structures induced by seismic loading. However, a reliable result from FEM is dependent on accurate measurement and interpretation of soil properties which is usually difficult to achieve.