Slope stability analysis of Southern slope of Chengmenshan copper mine, China

The engineering geology and hydrogeology in the southern slope of Chengmenshan copper mine are very complicated, because there is a soft-weak layer between two kinds of sandstones. Field investigations demonstrate that some instability problems might occur in the slope. In this research, the southern slope, which is divided into six sections (I-0, I-1, I-2, II-0, II-1 and II-2), is selected for slope stability analysis using limit equilibrium and numerical method. Stability results show that the values of factor of safety (FOS) of sections I-0, I-1 and I-2 are very low and slope failure is likely to happen. Therefore reinforcement subjected to seismic, water and weak layer according to sections were carried out to increase the factor of safety of the three sections, two methods were used; grouting with hydration of cement and water to increase the cohesion (c) and pre-stressed anchor. Results of reinforcement showed that factor of safety increased more than 1.15.