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Journal of Geotechnical Engineering Original Research

A Shear Strength Reduction Method for an Open Pit Slope Stability Analysis Based on Finite Element Method

  1. Dasmani Abdulai Department of Geological Engineering, Faculty of Geosciences and Environmental Studies, University of Mines and Technology
  2. Professor Michael Affam Department of Geological Engineering, Faculty of Geosciences and Environmental Studies, University of Mines and Technology,

Abstract

Slope stability assessment of open pit mines is critically important, since it forms part of the overall productivity and safety management strategy of the mines. The aim of this work is to investigate the overall stability conditions of three (3) open pits in Gold Fields Limited, Tarkwa Ghana. Field and laboratory investigations were conducted as well as empirical methods. Finite Element Analysis (FEA) in Rocscience was carried out using the Shear Strength Reduction technique. Results from the analysis revealed that the design planned for the pit walls was stable, with the critical Strength Reduction Factor (SRF) of 5.45, 5.3 and 2.6 respectively for Akontasi, Pepe and Teberebie. However, critically and actively unstable zones including potential failure mechanisms involving the oxides, transition and the fresh rocks have been revealed. From the analyses, there are potentials for progressive failures in the pits. These will be propagated from the critical zones in the rocks. However, to ensure safe and efficient mining operations and optimize cost-effectiveness, targeted dewatering systems especially dewatering wells and grout curtains should be installed in the critical deformation zones to reduce water influxes, infiltration and seepage into the pits. Also, effective monitoring programs should be intensified in the pit faces to avert any potential failure in the future.

Keywords

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