Cumming-Potvin, D, Wesseloo, J, Jacobsz, SW & Kearsley, E 2018, 'A re-evaluation of the conceptual model of caving mechanics', in Y Potvin & J Jakubec (eds), Caving 2018: Proceedings of the Fourth International Symposium on Block and Sublevel Caving
, Australian Centre for Geomechanics, Perth, pp. 179-190, https://doi.org/10.36487/ACG_rep/1815_11_Cumming-Potvin
The Duplancic conceptual model is the industry accepted model of caving and is the framework within which most results from numerical modelling and cave monitoring are interpreted. The Duplancic conceptual model implies that the damage ahead of the cave back decreases continuously with increasing distance from the cave surface. Evidence from a variety of sources indicates that this may not always be the case and that a discontinuous damage profile may be present.
Cumming-Potvin et al. (2016b) describes a physical modelling program which was undertaken to investigate the fracturing and propagation of the cave. The results of these centrifuge tests showed that caving could occur via a series of fractures oriented parallel to the cave surface and that the cave back progressed vertically via ‘jumps’ to the next successive parallel fracture. In Cumming-Potvin et al. (2016a), this caving mechanism was termed ‘fracture banding’. Multiple examples of a similar mechanism of failure were observed in literature. In addition, the patterns in microseismic event location indicate that fracture banding could be occurring in currently operating caving mines.
This paper examines evidence from a number of sources in the field of caving mechanics and presents an extended conceptual model of caving. The new model is able to account for the mechanism of fracture banding, along with the continuous style of failure from the Duplancic conceptual model. There are still many unknowns about the fracture banding mechanism and propagation of caves. These include the specific conditions under which the caving mechanism changes and whether the mechanisms lie on a continuum, or if there is a sharp, sudden change. Two conceptual models are presented: one which includes only that which is known about the mechanisms of cave propagation and one which speculates upon the factors involved and the underlying origins of the fractures.
Keywords: fracture banding, cave mining, physical modelling, cave monitoring, seismicity, centrifuge
Abolfazlzadeh, Y 2013, Application of Seismic Monitoring in Caving Mines - Case Study of Telfer Gold Mine, MSc thesis, Laurentian University, Sudbury.
Adams, GR & Jager, AJ 1980, ‘Petroscopic observations of rock fracturing ahead of stope faces in deep-level gold mines’, Journal of the South African Institute of Mining and Metallurgy, vol. 80, no. 6, pp. 204–209.
Brown, ET 2007, Block Caving Geomechanics, 2nd edn, Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Indooroopilly.
Carlson, G & Golden, R 2008, ‘Initiation, growth, monitoring and management of the 7210 cave at Henderson Mine - A case study’, Proceedings of MassMin 2008, Luleå University of Technology, Luleå, pp. 97–106.
Crook, T, Willson, S, Yu, JG & Owen, R 2003, ‘Computational modelling of the localized deformation associated with borehole breakout in quasi-brittle materials’, Journal of Petroleum Science and Engineering, vol. 38, pp. 177–186.
Cumming-Potvin, D 2018, An Extended Conceptual Model of Caving Mechanics, PhD thesis, The University of Western Australia, Perth.
Cumming-Potvin, D, Wesseloo, J, Jacobsz, SW & Kearsley, EP 2016a, ‘Fracture banding in caving mines’, The Journal of the Southern African Institute of Mining and Metallurgy, vol. 118, no. 8, pp. 753–761.
Cumming-Potvin, D, Wesseloo, J, Jacobsz, SW & Kearsley, EP 2016b, ‘Results from physical models of block caving’, Proceedings of MassMin2016, The Australasian Institute of Mining and Metallurgy, Melbourne, pp. 329–340.
Duplancic, P 2001, Characterisation of Caving Mechanisms Through Analysis of Stress and Seismicity, PhD thesis, The University of Western Australia, Perth.
Garza Cruz, TV & Pierce, M 2014, ‘A 3DEC model for heavily veined massive rock masses’, Proceedings of the 48th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria.
Glazer, S & Hepworth, N 2005, ‘Seismicity induced by cave mining, Palabora experience’, in Y Potvin & M Hudyma, Proceedings of the 6th International Symposium on Rockbursts and Seismicity in Mines, Australian Centre for Geomechanics, Perth,
Glazer, S & Townsend, P 2008, ‘The application of seismic monitoring to the future Lift 2 block cave at Palabora mining company’, Proceedings of MassMin 2008, Luleå University of Technology, Luleå, pp. 919–930.
Heslop, TG 1976, Rock Mechanics Aspects of Block Caving Chrysotile Asbestos Orebodies at Shabanie Mine, Rhosesia, MSc thesis, University of the Witwatersrand, Johannesburg.
Hudyma, M & Potvin, Y 2008, ‘Characterizing caving induced seismicity at Ridgeway gold mine’, Proceedings of MassMin 2008, Luleå University of Technology, Luleå, pp. 931–942.
Hudyma, M, Potvin, Y & Allison, D 2007a, ‘Seismic monitoring of the Northparkes lift 2 block cave—Part 1 undercutting’, Proceedings of the 1st International Symposium on Block and Sublevel Caving, The Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 303–334.
Hudyma, M, Potvin, Y & Allison, D 2007b, ‘Seismic monitoring of the Northparkes lift 2 block cave—Part 2 production caving’, Proceedings of the 1st International Symposium on Block and Sublevel Caving, The Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 335–354.
Jia, P, Yang, TH & Yu, QL 2012, ‘Mechanism of parallel fractures around deep underground excavations’, Theoretical and Applied Fracture Mechanics, vol. 61, pp. 57–65.
Li, LC, Tang, CA, Zhao, XD & Cai, M 2014, ‘Block caving-induced strata movement and associated surface subsidence: a numerical study based on a demonstration model’, Bulletin of Engineering Geology and the Environment, vol. 73, no. 4, pp. 1165–1182.
Lisjak, A, Tatone, B, Mahabadi, O & Grasselli, G 2012, ‘Block caving modelling using the Y-Geo hybrid finite-discrete element code’, Proceedings of MassMin 2012, Canadian Institute of Mining, Metallurgy and Petroleum, Westmount.
McNearny, RL & Abel, JF 1993, ‘Large-scale two-dimensional block caving model tests’, International Journal of Rock Mechanics and Mining Sciences, vol. 30, no. 2, pp. 93–109.
Nishida, T, Esaki, T & Kameda, N 1986, ‘Development of the base friction technique and its application to subsidence engineering’, Proceedings of the International Symposium on Engineering in Complex Rock Formations, Science Press, Beijing, pp. 386–392.
Panek, LA 1981, ‘Ground movements near a caving stope’, in D Stewart (ed.), Design and Operation of Caving and Sublevel Stoping Mines, Society of Mining Engineers of the AIME, New York, pp. 329–354.
Reyes-Montes, J, Pettitt, W, Pierce, M & Young, R 2010a, ‘Microseismic validation of jointed rock models in cave mining’, Proceedings of the 44th US Rock Mechanics Symposium, American Rock Mechanics Association, Alexandria.
Reyes-Montes, J, Sainsbury, B, Pettitt, W, Pierce, M & Young, R 2010b, ‘Microseismic tools for the analysis of the interaction between open pit and underground developments’, in Potvin (ed.), Proceedings of the 2nd International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 119–132.
Sharrock, G, Slade, N, Thin, I & Duplancic, P 2002, ‘The prediction of stress induced caving on a mining abutment’, Proceedings of the 1st International Seminar on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth.
Shemyakin, E, Fisenko, G, Kurlenya, M, Oparin, V, Reva, V, Glushikhin, F, Rozenbaum, M, Tropp, E & Kuznetsov, YS 1986a, ‘Zonal disintegration of rocks around underground workings, part 1: Data of in situ observations’, Journal of Mining Science, vol. 22, no. 3, pp. 157–168.
Shemyakin, E, Fisenko, G, Kurlenya, M, Oparin, V, Reva, V, Glushikhin, F, Rozenbaum, M, Tropp, E & Kuznetsov, YS 1986b, ‘Zonal disintegration of rocks around underground workings. Part II: Rock fracture simulated in equivalent materials’, Journal of Mining Science, vol. 22, no. 4, pp. 223–232.
Tibbett, JD, Suorineni, FT & Hebblewhite, BK 2015, ‘Investigating block caving geomechanics using seismic space-time sequences and virtual reality scientific visualization’, Proceedings of the 49th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria.
Tibbett, JD, Suorineni, FT & Hebblewhite, BK 2016, ‘Understanding damage source mechanisms in a caving system using virtual reality scientific visualisation’, Proceedings of MassMin 2016, The Australasian Institute of Mining and Metallurgy, Melbourne,
Vyazmensky, A, Elmo, D, Stead, D & Rance, JR 2007, ‘Combined finite-discrete element modelling of surface subsidence associated with block caving mining’, in E Eberhardt, D Stead & T Morrison, (eds), Rock Mechanics: Meeting Society's Challenges and Demands, vol. 1, Taylor & Francis Group, Boca Raton, pp. 467–476.
Woodward, K 2011, Investigation of Block Caving Mechanics through the Interpolation of Seismic Occurrence and Source Parameters, honours thesis, The University of Western Australia, Perth.