Authors: Watton, JW; Weir, FM

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Watton, JW & Weir, FM 2023, 'Using discrete fracture networks to understand wedge failures for open pit slope design', in PM Dight (ed.), SSIM 2023: Third International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, pp. 491-504,

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A wedge failure is defined as the sliding of a rock block on the line of intersection of two discontinuities. This failure mechanism can occur over a wide range of geological and geometric conditions. This paper presents the ground conditions and existing slope performance at a case study site where bench and multibench slope stability is controlled by wedge failures. The study compares the probability of wedge failure from mapping and photogrammetry data with the existing performance of the current pit slope using industry-accepted methods. The existing slope performance was assessed using photogrammetry techniques built from aerial drones to estimate the proportion of pit slope that failed. Slope stability was also assessed using a discrete fracture network approach, with the resultant predicted area of the failed slope compared against the current slope performance measured by photogrammetry. The study highlights the importance of understanding size and spatial relationships between defect sets for wedge formation and the implications for bench and inter-ramp scale slope design.

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

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