Stability analysis of rock-fill tailing dam: an Indian case study

Abstract

This paper presents the comprehensive stability analysis of the rock-fill tailing dam constructed at Rampura Agucha zinc mine in Rajasthan, India. The results of the feasibility study carried out prior to the expansion of the dam height from existing 27 to 51 m have been presented. The final cross-section of the tailing dam was arrived based on the extensive stability analysis considering both the upstream and downstream methods of embankment rising. The factor of safety values was calculated from Bishop’s simplified method, Janbu’s method and Spencer’s method by considering the circular failure surfaces. Further, the dynamic stability analyses were also carried out using the pseudostatic approach. The results from the limit equilibrium approaches were validated with the shear strength reduction technique using finite difference-based Fast Lagrangian Analysis of Continua in 2D analysis. The factor of safety values calculated from the different approaches was found to be in good agreement with each other. In addition, the safety and stability of the tailing dam was found unaffected by the ongoing mining activities as the observed peak particle velocity at the site was less than 15 mm/s. Analysis of the last 25 year’s rainfall data suggested that the designed freeboard of 2 m above settled tailings can accommodate a single rainfall spell of approximately 2000 mm without endangering its structural stability.