Geotechnical lessons learnt during undercutting in deep caving at Cadia Operations

Authors: Lett, J

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DOI https://doi.org/10.36487/ACG_repo/2465_02

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Lett, J 2024, 'Geotechnical lessons learnt during undercutting in deep caving at Cadia Operations', in P Andrieux & D Cumming-Potvin (eds), Deep Mining 2024: Proceedings of the 10th International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 109-136, https://doi.org/10.36487/ACG_repo/2465_02

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Abstract:
Cadia Operations (wholly owned by Newmont Mining) initiated block caving with the Ridgeway Deeps block cave (RWD) at depths below 1,000 m in highly stressed conditions using industry leading methods, these practices were extending to the Cadia East orebody. The mine design during the Cadia East pre-feasibility and feasibility study selected panel caving as the preferred method. These initiatives have driven advancements in deep, high-stress underground caving mining. This paper details the development and refinement of advanced and post undercut design methodologies in demanding geotechnical contexts. It assesses performance and geotechnical characteristics, highlighting challenges in cave initiation, undercut sequencing, rock mass response in brittle lithologies, seismic response, ground support performance and geotechnical hazard management. This paper illustrates how advanced and post undercut techniques can be implemented safely with effective risk controls when managing the rock mass response during undercutting. It proposes critical parameters and metrics for an unbiased comparison of these techniques in feasibility studies, aiming to establish a comprehensive checklist for use in the planning phase. This analysis is underpinned by an extensive literature review and benchmarked mine site data.

Keywords: advanced undercut, post undercut, caveability, core disking, undercut veranda, rock mass response, seismicity, ground support, stress abutment

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