Evaluation of Stability of Dump Slopes Through Observational and Mumerical Model Approach – Case Study

Abstract

This paper presents a case study of evaluation of dump slopes in a typical chromate mine in India including observational approaches and numerical modeling besides a critical review of recent accidents due to dump and bench slope failures in India. As per the numerical models, The FOS achieved for typical sections for the North and South dump exceeded 1.2 indicating the stability of dumps in drained condition of slopes except for one section considered in the analysis. As the FOS for the vertical Section - 3000E for the North dump was 1.15, efforts may be made to regrade the dump, accordingly to minimize any scope of further reduction of FOS. However, in saturated condition of slope, there is a possibility of reduction of FOS, which may lead to failure of slope, and hence proper drainage is highly solicited. There is a scope of local slope failure near some of the stations in North and south dumps, in rainy season due to water saturated conditions. Therefore, slope monitoring should be continued to detect the onset of failure so that early and effective stabilization measures can be taken. It is also recommended to regularly produce up-to-date and accurate dump geometry on daily basis for the profile near the target points showing considerable displacement, or if feasible a system for continuous monitoring and construction of Gabion wall may be considered for improved safety.