Oredrive stability in a sublevel caving project for Jwaneng mine

Authors: Álvarez, C; Barra, C; Lorig, L; Dunn, MJ; Kebatsetse, LQ Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2645_25

Cite As:
Álvarez, C, Barra, C, Lorig, L, Dunn, MJ & Kebatsetse, LQ 2026, 'Oredrive stability in a sublevel caving project for Jwaneng mine', in A van As, D Cumming-Potvin & J Wesseloo (eds), Caving 2026: Proceedings of the Sixth International Conference on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 1-14, https://doi.org/10.36487/ACG_repo/2645_25



Abstract:
The Jwaneng underground mine is progressing through a pre-feasibility study, targeting the extraction of three kimberlite pipes to an ultimate depth of approximately 1,000 m below ground surface. Open pit mining at Jwaneng is expected to conclude by 2036, with a subsequent transition to underground mining methods. The underground project involves a combination of mining methods, starting with the extraction of open pit wedges using variants of sublevel retreat, followed by deepening through sublevel caving and block caving in one of the kimberlite pipes. Three-dimensional numerical modelling provides a robust framework for assessing the impact of mining on the surrounding rock mass. Mine-scale models developed using a hybrid methodology combining FLAC3D and gravity flow can capture slope failure progression and stress redistribution affecting underground workings. This study focuses on oredrive stability, quantified through tunnel closures and mining-induced strains. Ground support performance is implicitly evaluated based on tunnel strain thresholds. The numerical modelling approach integrates large-scale mining geometry with localised resolution for tunnel closure assessment. Oredrive stability is evaluated for three kimberlite pipes under different spacing scenarios (15 m, 18 m and 21 m centre-to-centre). A strain-softening Hoek–Brown constitutive model is used in the analyses, with no intact rock swelling behaviour assumed for the kimberlite. Sensitivity analyses addressing uncertainty in rock mass properties, including post-peak parameters, provide a range of expected responses and serve as a numerical reference for similar underground mining operations.

Keywords: sublevel caving, Jwaneng mine, oredrive stability

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