Probabilistic Slope Stability Analysis of Coal Mine Waste Rock Dump

Coal mine waste rock is generated during coal extraction and is usually disposed of in non-engineered dumps. The dumps are extended vertically to 100–120 m height to reduce the spatial footprint. The waste mass generally consists of loose, cohesionless material associated with high heterogeneity, so the dumps are prone to slope failures. A typical dump configuration in Jharkhand, India (total height, H = 125 m; slope angle, θ = 3V:1H) is considered for evaluation in this study. A 2D limit equilibrium numerical analysis is performed to estimate the slope stability. A parametric study is conducted to understand the effect of bench height (H), bench width (W), and slope angle (θ) on the factor of safety. The heterogeneity of the material is analyzed using the probabilistic descriptors (mean, standard deviation, and coefficient of variation (CoV)). The influence of CoV on the shear strength parameters is studied at various intervals ranging from 10 to 80% and compared using Monte Carlo simulation and alternative point estimate methods. Further, the modified slope geometry and the benches are recommended as remediation methods to achieve the desired safety factor. The results provide valuable insights into understanding the influence of slope geometry and material heterogeneity during the stability analysis of coal mine dumps.