St-Hilaire, P, Grenon, M & Wilson, B 2025, 'Optimising ramp design using discrete fracture network cost-based analysis', in JJ Potter & J Wesseloo (eds), SSIM 2025: Fourth International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, https://doi.org/10.36487/ACG_repo/2535_40
(https://papers.acg.uwa.edu.au/p/2535_40_Grenon/)
Abstract: Mining ramps are critical infrastructures in open pit mines, facilitating the efficient transport of ore and waste materials, while ensuring the safe movement of equipment and personnel. Wedge instabilities along these ramps can reduce rolling width, potentially leading to lane closures that significantly impact productivity, profitability, and safety. 
Discrete fracture network (DFN)-based wedge stability analyses account for the stochastic nature of fracture location, size, and orientation within the rock mass. Quantifying back-breaks along bench crests, using DFN modelling, provides valuable insights into the post-excavation bench slope profile. This approach enables a more accurate prediction of instability impacts on ramp width and the formation of bottlenecks along ramps. The cost associated with bottleneck formation along a ramp can be computed for various slope design configurations.
For a worked example using typical geomechanical and operational data from an active mine where wedge failure is commonly occurring at the crest of benches, a DFN-cost-based back-break analysis reveals how different bench angles influence bottleneck formation, demonstrating that optimal decision-making should not rely solely on geometric stability. A purely structural approach might suggest a linear cost increase with steeper bench face angles (BFA). An integrated economic analysis indicates an exponential cost rise due to transport inefficiencies caused by the increasing number and length of single-lane sections. The study concludes that integrating cost analysis with DFN modelling is a valuable tool for understanding the financial implications of rock instabilities along mining ramps, ultimately improving the ramp design process.

Keywords: open pit, ramp design, bench stability, DFN modelling, back-breaks, cost analysis