Stability Assessment and Optimal Excavated Design of a Rock Slope in an Opencast Limestone Mine

Abstract

The stability of rock slopes in an opencast limestone mine throughout the mining process was investigated using the limit equilibrium approach (SlopeW). The optimal excavation method with a substantially steeper slope angle of 450 rather than 350 was successfully accomplished at the critical geological section of the pit slope under numerous geologically disturbed area such as joints, faults and folds on a geotechnical basis in order to ensure adequate stability against any failure while working in the mine. The primary objective of this paper is to use the limit equilibrium approach in the SlopeW programme to predict the slope’s safety factor and critical failure surface geometry due to the imposed of a surcharge loading of dump on top of the open pit slope for a 110m deep rock cut in the limestone mine. Geotechnical studies covering field geological mapping, laboratory experiments on rock samples cored from exploration drilling and different rock blocks retrieved straight from the mine were used to determine the physico-mechanical characteristics of the rock components, and numerical analysis using limit equilibrium technique (SlopeW) was carried out. It is also recommended that no activity or construction take place on the top of the pit slope crest in order to prevent further slope failures in old scheme and shifting dump 25m away from the top of pit slope for future safe workings in the mine. © 2023, Books and Journals Private Ltd.. All rights reserved.