Assessment of rock slope stability at Cham-Shir Dam Power Plant pit using the limit equilibrium method and numerical modeling

There is global concern about the stability of rock slopes in open pit mines while the limit equilibrium technique used for modeling complex geometries and forces fails to provide a complete understanding of the behavior of rock slopes due to its inherent shortcomings. However, numerical approaches to modeling complex rock structures have improved the general understanding of these slope structures. In this study, geological and geotechnical data were obtained from both exploration drill holes and laboratory tests using face mapping and scanline surveys to reveal three major joint sets related to the regional tectonic history at the Cham-Shir dam power plant pit in Iran. The joints play an important role in the slope stability of the open pit, notably in terms of planar and wedge failures. Moreover, both the limit equilibrium technique and the discrete element method were employed to analyze the stability of the Cham-Shir dam power plant pit in an attempt to evaluate its behavior under both supported and unsupported conditions in the three modes of continuous rock mass, rock mass with two joint sets, and rock mass with three joint sets. Results show that the rock mass is stable in the continuous mode. The possible failure must, therefore, be due to the structure type and the joint sets at the site. To address the requirements and to resolve the problem, a simulation study was conducted. Based on the findings, stage by stage excavations are recommended for the study site.