Watton, J, Weir, F & Fowler, M 2025, 'Using discrete fracture networks to assess how defect size and other variables 
affect the formation of wedge failures in open pits', 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_38
(https://papers.acg.uwa.edu.au/p/2535_38_Watton/)
Abstract: Wedge failure is the sliding of a rock block on the line of intersection of two discontinuities oriented to form a wedge, and is influenced by geological and geometric factors. This paper compares traditional industry-accepted pit slope design methods with a discrete fracture network (DFN) approach. The geotechnical model and observed performance from a case study site are presented and used to benchmark the analysis results. 
Major discontinuities measured from photogrammetry and pit face mapping data from the case study site were used for the analysis, and the observed performance was assessed from a photogrammetry point cloud created using drones. 
Both the industry-accepted and DFN methods indicated that the probability of failure increases with steeper slope angles, however, the industry-accepted methods overestimated this probability compared to the observed slope performance. The DFN models were more closely aligned with the observed slope performance. 
The study highlights that discontinuity size and the spatial distribution of discontinuity sets are key drivers of the potential for wedge instability and the resulting slope performance, which have flow-on impacts for developing reliable pit slope designs.

Keywords: wedge, discrete fracture network, open pit slope design