A Case Study of Probabilistic Seismic Slope Stability Analysis of Rock Fill Tailing Dam

The article presents the case history of expansion of rock fill tailing dam of the Rampura-Agucha zinc mine in Rajasthan, India. Before raising the height of the dam from 27 m to 54 m, a detailed seismic stability analysis was performed considering the spatial variability of the soil. The safety values and the probability of failure were calculated using the Monte Carlo simulation method. All the analyses were carried in a 2-D limit equilibrium-based SLIDE software using Spencer's method. The cohesive strength (c), the angle of friction and the acceleration due to earthquakes were considered as the random variable. The final slope geometry was created after the seismic stability analysis of the upstream and downstream slopes. For the critical geometry of the slope, the observed factor of safety values was found to be higher than the values specified in the ANCOLD. The probability of failure value was found to be less than 8%. The newly constructed rock fill dam has already sustained three Monsoon rains and still continues to be performing at its best condition.