Discrete fracture network application to rock slope stability in an open pit mine

The stability of rock slopes in open pit mines is crucial for the safety and efficiency of the mining operation. Conventional stability analysis methods, such as kinematic and limit equilibrium analyses, primarily focus on identifying structural failure mechanisms and evaluating their factors of safety. Although insightful, these approaches do not accurately estimate failure volumes and block locations due to their limited consideration of joint frequency and persistence, which are key parameters in understanding block geometries. Discrete fracture network (DFN) modelling addresses these limitations by explicitly simulating rock mass discontinuities in 3D, which automatically incorporates joint spacing and persistence. This paper presents the results of a detailed case study from the Obra South Pit of Asante Gold Chirano Limited, an open pit mine in Ghana. DFN models were developed and compared with conventional methods and finite element modelling. It is shown that the results from the DFN analysis align with field observations, underscoring the critical role of persistence in pit stability analysis. Finally, the study evaluates the influence of joint persistence on factors of safety and failure volumes. It offers new insights into slope stability analysis and showcases the advantages of DFN modelling in open pit mining.