Optimization and slope stability coal mine with dewatering system using limit equilibrium method

Abstract

Mining activities related to excavation or landfill will always face problems with slopes, both in the form of working slope and final slope, in addition the groundwater factor in the rock layer increases the burden by filling pores and reducing friction inter-grain influences the slope stability. The slopes must be analyzed for stability to prevent landslide hazards because they involve work safety, equipment safety, and smooth production. PT. XYZ is a coal mining company located in the Lilin river, South Sumatra, planning to optimize and stabilize the final slope to a depth of 120 m. Geotechnical drilling has been carried out as many as 3 points with a total depth of 270 m and 80 samples of rock and soil testing. The results of optimization and stability of the slope by conducting dewatering at each elevation to obtain optimal slope conditions at PT. XYZ can be done up to elevation of -130 meters above sea level with a depth of 142 meters with an angle of 35° with the condition of the ground water level must be maintained at the halfway point of the slope (GWL Chart No. 3). Under water saturated conditions (GWL Chart No. 5) at the same elevation the permissible angle is only 25° with a final slope height of 136 m.