Slope stability in open pit mines is an important issue. Most open pit coal mines are located in Kalimantan in which rainfall is very high and as such so is the probability of slope failure. It has been well accepted that slope failure risk consists of probability times consequence of the slope failure. In order to have a study on the consequences of slope failure as a function of various geotechnical parameters, a laboratory scale investigation was conducted. A centrifuge with a diameter of 3.65 m, a load capacity of 3 kN and a maximum rotation of 70 rpm was designed and built in house by the Laboratory of Geomechanics & Mining Equipment of ITB in Indonesia. Dimensional analysis was used to scale down the model from a real slope condition in an open pit coal mine. The material used in this study is consolidated clayey sand with slope heights of 10 cm, slope angles of 45°, 60° and 75°; the centrifugal acceleration were 0.15g, 0.23g, 0.33g; 0.46g, 0.59g, 0.75g, and 0.93g. By running the centrifuge at different levels of rpm and slope dimensions, the volume and mode of the slope failures can be obtained and can be used for the input data for assessing risk analysis of slope stability in an open pit coal mine. In order to confirm the results of the physical modeling tests, numerical modeling using the limit equilibrium method and direct monitoring in the field are also carried out.
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