Stability Analysis of a Pentahedral Rock Wedge Governed by Multi-Discontinuities

In this study, an unstable rock slope has been investigated. To evaluate the stability of the pentahedral rock wedge with multi-slip surfaces, an approach based on the limit equilibrium method has been used. The slope has been divided into two parts for the establishment of the model: an upper wedge block and a lower pentahedron block. Namely, a three-dimensional space problem can be resolved into a local equilibrium problem of several sub-blocks. Then, the geometric parameters can be determined, and the mechanical analysis can be carried out. Finally, the minimum safety factor can be calculated by using the optimization method. This proposed approach has been applied to analyze the stability of the unstable rock slope before and after reservoir impoundment. The results show that the safety factor is significantly smaller after reservoir impoundment. The safety factor can meet the safety control standards of specifications without considering the extreme conditions of combined rainstorm and seismic force under the proposed reservoir water level.