BACK ANALYSIS OF RAINFALL-INDUCED WASTE DUMP FAILURE USING COUPLED HYDRO-MECHANICAL ANALYSIS – A CASE STUDY IN COAL MINE

Abstract

Managing the waste dumps has become a significant challenge, along with increasing mining production. Maintaining waste dump stability is vital to prevent failures that could lead to economic losses, environmental harm, and safety hazards. This study investigates the stability of waste dumps in open-pit coal mining operations, focusing on the impact of rainfall on dump stability. The objective was to evaluate a strain-based approach for predicting waste dump failures, accounting for changes in soil properties during rainfall events. A coupled hydro-mechanical framework was used to back-analyze the historical impact of rainfall on waste dump stability. The results showed strain values ranging from 2.79% to 7.36% during progressive slope failure. The weak nature of the waste dump material, with compressive strengths of less than 1 MPa and poor rock mass quality, enabled the development of an approximate maximum strain threshold graph. These findings could enhance predictive capabilities for waste dump stability and bridge the gap by utilizing coupled hydro-mechanical analysis, ultimately improving understanding and safety in waste dump operations.