Slope Stability Analysis of Sarcheshmeh Copper Mine West Wall Under Seismic Loads

Abstract

The role of slope stability in design, implementation and prediction of risk is very significant. From an economic point of view, higher slope angles would result in reduction of stripping ratio, return time of investment, and increase of the minable mineral reserves. The presence of natural disasters such as earthquakes is very important for the sustainability of open and underground structures. Earthquake is one of the major factors affecting the instability of natural and artificial slopes. Often, instabilities occurred in slopes due to earthquake cause large amounts of material collapse into open pit mines, and thus halt the mine production. Sarcheshmeh Copper Mine is one of the most important and biggest active mines of Iran which has an important contribution to copper production in the world. Presence of many faults and extreme weathering accompanied by the fact that the mine is located in a seismically active zone, confirms the requirement of slope dynamic stability analysis in addition to static analysis. In this paper, the finite difference method is used for the stability analysis of rock mass under static and earthquake loadings. The static analysis is performed and modelling results are presented in terms of safety factor and displacement history of important locations of the wall. Slope dynamic stability analysis under seismic loads is implemented based on time response method. In order to apply earthquake loading, the 2003 Bam earthquake record is utilized. The conclusions obtained by the time response analysis are displayed in the form of vertical and horizontal displacements histories of criticed locations within the slope. The results of analysis confirm the overall stability of slope. The displacements obtained by the time response analysis method are convergent and within the permitted range, such that there is no oscillation after the earthquake load is applied over the time. Finally, a sensitivity analysis for some input parameters including wall slope angle, underground water table, cohesion and internal friction angle of the rock mass is performed to examine and assess the impact of these parameters on the wall displacements field.