Optimisation of Overburden Dump Capacity using Limit Equilibrium and Finite Element Techniques

Abstract

In India, majority of coal demand is met by opencast mining production. The continuously increasing demand of coal has led to rapid opencast mining activities with high stripping ratio of 1:12 to 1:15, in turn requiring large quantities of overburden to be mined and its storage poses serious problem. Recently, few dump failures have taken place. Destabilisation of overburden dump hampers the production of the mine. On the other hand, under utilisation of storage capacity of the dump gives rise to additional land requirement. Therefore, for efficient functioning of dump, it is important to optimally utilise its capacity commensurate with stability. In this study, an internal dump at one of the mines of Coal India Limited has been studied. Two different techniques have been used to simulate and analyse the existing dump for its storage capacity and safety. The dump has been optimised maintaining the stability and safety requirements of the slope, and has been studied for its stability using different methods. A comparison of its factor of safety obtained from each method of analysis has been presented. From the study, an increase in the dump capacity of about 14% has been proposed by the numerical modelling technique, which further encourages possible savings in land. Hence, the paper seeks to optimise the existing dump and provide an economical and safe solution to the issues of land acquirement in India for overburden storage. Keywords—