DOI https://doi.org/10.36487/ACG_rep/1925_35_Potvin
Cite As:
Potvin, Y, Hadjigeorgiou, J & Wesseloo, J 2019, 'Towards optimising ground support systems in underground mines', in J Hadjigeorgiou & M Hudyma (eds),
Ground Support 2019: Proceedings of the Ninth International Symposium on Ground Support in Mining and Underground Construction, Australian Centre for Geomechanics, Perth, pp. 493-502,
https://doi.org/10.36487/ACG_rep/1925_35_Potvin
Abstract:
There is a large body of literature describing different methods for designing ground support systems for underground excavations. Ground support design methods are commonly grouped in three classes—namely, analytical, empirical and numerical modelling methods.
A comprehensive review of practices in Australian and Canadian mines (Potvin & Hadjigeorgiou 2016) has shown that the design of ground support is largely the result of the evolution of and adjustments to an initial design. The initial design relies mainly on two methods: the Grimstad–Barton (Grimstad & Barton 1993) empirical chart and the RocScience software UnWedge, based on a limit equilibrium wedge analysis defined by continuous large geological structure. The optimisation process is largely reactive and involves modifying the ground support systems to cater for ground conditions that differ from those initially anticipated or replacing ground support elements to improve performance. Sometimes the decision is backed up by numerical modelling analyses in anticipation of stress changes as a result of mining. Nevertheless, a systematic engineering methodology is rarely employed to optimise ground support systems in underground mines.
An optimum ground support system can be defined as the lowest cost system, including installation cost and productivity factors such as development mining rates, which can achieve a tolerable Probability of Failure (PoF) during the service life of an excavation. A further requirement is that such a system will minimise the need for rehabilitation.
The above definition implies that no matter which design method is applied, a probabilistic assessment is required to ascertain whether the ground support design meets the target PoF. This paper outlines userfriendly mXrap-based tools developed within the scope of the Australian Centre for Geomechanics’s Ground Support System Optimisation research project.
Keywords: support design, rockfalls, probabilistic approach, Probability of Failure
References:
Bahrani, N & Hadjigeorgiou, J 2018, ‘Influence of stope excavation on drift convergence and support behavior: insights from 3D continuum and discontinuum models’, Rock Mechanics and Rock Engineering, vol. 51, pp. 2395–2413.
Beauchamp, KJ, Carvalho, J, Castro, L & Morrison, DM 1998, Probabilistic Analysis for Ground Support for Underground Mines, Canadian Institute of Mining, Montreal.
Choquet, P & Hadjigeorgiou, J 1993, ‘Design of support for underground excavations’, in J Hudson (ed.), Comprehensive Rock Engineering, vol. 4, Pergamon Press, Oxford, pp. 313–348.
Dunn, MJ, Earl, P & Watson, J 2008, ‘Support design using probabilistic keyblock methods’, in TR Stacey & D Malan (eds), Proceedings 6th International Symposium on Ground Support in Mining and Civil Engineering Applications, The Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 623–636.
Grenon, M & Hadjigeorgiou, J 2003, ‘Drift reinforcement design based on discontinuity network modelling’, International Journal of Rock Mechanics and Mining Sciences, vol. 40, pp. 833–845.
Grenon, M & Hadjigeorgiou, J 2012, ‘Applications of fracture system models (FSM) in mining and civil rock engineering design’, International Journal of Mining, Reclamation and Environment, vol. 26, no. 1, pp. 55–73.
Grimstad, E & Barton, N 1993, ‘Updating the Q-system for NMT’, in C Kompen, SL Opsahl & SL Berg (eds), Proceedings of the International Symposium on Sprayed Concrete, Norwegian Concrete Association, Oslo, p. 21.
Hadjigeorgiou, J & Grenon, M 2017, ‘Drift reinforcement design based on Discrete Fracture Network (DFN) modelling’, in Feng, X-T (ed.), Rock Mechanics and Engineering, Taylor & Francis Group, Milton Park, pp. 123–146.
Harris, PC & Wesseloo, J 2015, mXrap, version 5, computer software, Australian Centre for Geomechanics, The University of Western Australia, Perth,
http://mxrap.com
Joughin, WC, Jager, A, Nezomba, E & Rwodzi, L 2012 ‘A risk evaluation model for support design in Bushveld Complex underground mines: Part II–Model validation and case studies’ The Journal of The Southern African Institute of Mining and Metallurgy, vol. 112, February, pp. 95–104.
Karampinos E, Hadjigeorgiou, J & Turcotte, P 2016, ‘Discrete element modelling of the influence of reinforcement in squeezing conditions in a hard rock mine’, Rock Mechanics and Rock Engineering, vol. 49, pp. 4869–4892.
Potvin, Y & Hadjigeorgiou, J 2016, ‘Selection of ground support for mining drives based on the Q-System’, in E Nordlund, T Jones & A Eitzenberger (eds), Proceedings of the Eighth International Symposium on Ground Support in Mining and Underground Construction, Luleå University of Technology, Luleå.
Sweby, G, Dight, PM, Potvin, Y & Gamble, N 2016, ‘An instrumentation project to investigate the response of a ground support system to stoping induced deformation’, in Proceedings of the Eighth International Symposium on Ground Support in Mining and Underground Construction, Luleå University of Technology, Lulea.
Thompson, AG & Windsor, CR 2007, ‘Block formation around excavations using deterministic and probabilistic methods’, Proceedings of the 11th ISRM Conference, International Society for Rock Mechanics and Rock Engineering, Lisbon.
Tyler, DB, Trueman, R & Pine, RJ 1991, ‘Rockbolt support design using a probabilistic method of keyblock analysis’, Proceedings of the 32nd U.S. Symposium on Rock Mechanics, A.A. Balkema, Rotterdam
Wesseloo, J 2016, ‘The use of elastic superposition as part of a multi-tiered probabilistic ground support design approach’, in E Nordlund, T Jones & A Eitzenberger (eds), Proceedings of the Eighth International Symposium on Ground Support in Mining and Underground Construction, Luleå University of Technology, Luleå.
Wesseloo, J & Grenon, M 2017, mXrap software app: Intact Rock Characterisation, alpha, The Australian Centre for Geomechanics, The University of Western Australia, Perth,
Windsor, CR 1999, ‘Systematic design of reinforcement and support schemes for excavations in jointed rock’, in E Villaescusa, CR Windsor & AG Thompson (eds), Proceedings International Symposium on Ground Support and Reinforcement Practice in Mining, Kalgoorlie, Balkema, Rotterdam, pp. 35–58
Windsor, CR & Thompson, AG 1992, ‘Reinforcement design for jointed rock masses’, Proceedings of the 33rd U.S. Symposium on Rock Mechanics, A.A. Balkema, Rotterdam.