Discrete Fracture Network Application to Rock Slope Engineering
Sponsor: Rocscience Ltd and MITACS
MSC Thesis, Elvis Karikari Mensah
The stability of rock slopes is a critical concern in both civil and mining engineering applications due to safety hazards and economic implications associated with slope failures. Conventional slope stability analysis methods such as kinematic and limit equilibrium analyses primarily focus on identifying structural failure mechanisms and determining a factor of safety. However, these methods often fail to accurately estimate the failure volume and its spatial distribution due to their limited consideration of joint frequency and persistence, which are key parameters in understanding failure behaviour. Discrete Fracture Network (DFN) modelling addresses these limitations by explicitly simulating rock mass discontinuities in three dimensions, incorporating parameters such as joint spacing and persistence. DFN models optimize the use of statistical data related to discontinuity characteristics, enabling the construction of both deterministic and stochastic fracture networks
This thesis is divided into two parts: civil engineering applications and mining applications. The first part focuses on case studies from two road cuts in far south-west of Saudi Arabia near the city of Jazan, where DFN modelling is used to improve slope stability assessments by integrating discontinuity parameters into three-dimensional models. The second part examines a case study of the Obra South Pit of Asante Gold Chirano Limited in Ghana, demonstrating the benefits of DFN modelling in open pit slope stability analysis.
The results from the DFN analyses demonstrate their capability to align closely with field observations, underscoring the significance of joint persistence in slope stability assessment. Additionally, DFN modelling enables the estimation of failure volume, providing insights that conventional methods lack. This thesis evaluates the effects of joint spacing and persistence on the factor of safety and failure volume, offering a more comprehensive approach to stability analysis. Finally, the advantages and limitations of DFN modelling in rock slope stability assessments are highlighted, with discussions on potential areas for improvement and optimization in both civil and mining engineering applications.