Stability Analysis of Tailings Dam Using Finite Element Approach and Conventional Limit Equilibrium Approach

Abstract

The probability of failure in tailings dam is generally found to be much greater than the conventional water retaining dams. Slope instability is one of the major reasons, contributing more often to the failure of these tailings dam. Due to this reason, the stability of tailings dam has drawn much attention as significant numbers of tailings dam’s failure have been reported worldwide in the recent years. The present work focuses on evaluating the stability of existing tailings dam by using finite element method (FEM) as well as conventional limit equilibrium methods (LEMs) under static loading conditions. Shear strength reduction (SSR) technique is incorporated (by using 2D finite-element based package RS²) in order to observe the potential modes of failure. Further, Rocscience SLIDE-2D is utilised to evaluate the stability of dam embankments by LEM. The results obtained from the analysis utilizing both LEM and FEM are compared in terms of their global factor of safety (FOS) and strength reduction factor (SRF) respectively. Further, an attempt is made to explore the stability of different types of tailings dam, based on their method of construction (i.e., upstream (U/S) method and downstream (D/S) method). The results obtained from LEM and FEM are found be in good agreement with each other. It is observed that the FOS and SRF values decrease as the height of embankment is raised. In addition, the failure surface is found to be circular in FEM for most of the critical slopes, which supports the assumptions of circular slip surface considered in LEMs based analysis. In addition, D/S slope is found to be more susceptible to failure than the U/S slope, for both U/S and D/S methods of construction.