Authors: Elmo, D; Farahmand, K; Rogers, S; Veltin, K; Lett, J

Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2205_93

Cite As:
Elmo, D, Farahmand, K, Rogers, S, Veltin, K & Lett, J 2022, 'An effective numerical method to understand different aspects of cave preconditioning ', in Y Potvin (ed.), Caving 2022: Fifth International Conference on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 1337-1350, https://doi.org/10.36487/ACG_repo/2205_93

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
Full-scale forward geomechanical modelling of the caving process, remains problematic, challenging the key principles of numerical analysis applied to rock engineering problems: i) a model is not and cannot be a perfect imitation of reality; and ii) numerical modelling is driven by questions. This paper presents a simpler numerical solution that follows fundamental modelling principles, whereby simple models are used to analyse different aspects of a given problem and to determine which process need to be considered explicitly and which can be represented in an average way. Synthetic cave models (SCM) are introduced as a suitable modelling approach for optimising hydrofracturing design and draw strategy by investigating a range of possible scenarios. The SCMs can be considered a scaled down version of a large, although simplified, mine scale problem. In the current paper, we have used SCM at different scale in terms of the adopted width of the simulated undercut. All modelling scenarios consider the development of a relatively deep cave located at a depth of 1,400 m. Due to their simple and conceptual nature, these models allow us to analyse different aspects of cave mechanics, including cave initiation, cave propagation, effectiveness of preconditioning, draw sequence and caving rates.

Keywords: block caving, preconditioning, numerical modelling

References:
Beck, D & Pfitzner, M 2008, ‘Interaction between deep block caves and existing, overlying caves or large open pits’, Proceedings of the 5th International Conference and Exhibition on Mass Mining (MassMin2008), Luleå University of Technology, Luleå, pp. 381–391.
Beck, DA & Putzar, G 2011, ‘Coupled flow-deformation simulation for mine scale analysis of cave initiation and propagation’ Proceedings of the 12th ISRM Congress, International Society for Rock Mechanics and Rock Engineering, Lisbon.
Bieniawski, Z 1989, Engineering Rock Mass Classifications: A Complete Manual for Engineers and Geologists in Mining, Civil, and Petroleum Engineering, John Wiley and Sons, Hoboken.
Borges, JL 1946, ‘On Exactitude in Science’, Los Anales de Buenos Aires, vol. 3.
Brzovic, A & Villaescusa, E 2007, ‘Rock mass characterization and assessment of block-forming geological discontinuities during caving of primary copper ore at the El Teniente mine, Chile’, International Journal of Rock Mechanics and Mining Sciences, vol. 44, no 4, pp. 565–583.
Deere, DU, Merritt, AH & Coon, RF 1969, Engineering classification of in-situ rock, technical report AFWL-TR-67-144, Air Force Weapons Laboratory, Air Force Systems Command, Kirtland Air Force Base, New Mexico.
Elmo, D, Stead, D & Rogers, S 2008, ‘Quantitative analysis of a fractured rock mass using a discrete fracture network approach: Characterisation of natural fragmentation and implications for current rock mass classification systems’, Proceedings of the 5th International Conference and Exhibition on Mass Mining (MassMin2008), Luleå University of Technology, Luleå,
pp. 1023–1032.
Elmo, D, Rogers, S, Beddoes, R & Catalan, A 2010, ‘An integrated finite/discrete element method – discrete fracture network synthetic rock mass approach for the modelling of surface subsidence associated with panel cave mining at the Cadia East underground project’, in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 167–179,
Elmo, D, Vyazmensky, A, Stead, D & Rogers, S 2012, ‘Applications of a finite discrete element approach to model block cave mining’, in L Ribeiro e Sousa, E Vargas, MM Fernandes & R Azevedo (eds), Innovative Numerical Modelling in Geomechanics, 1st edn, pp. 355–371.
Elmo, D, Rogers, S, Dorador, L & Eberhardt, E 2015, ‘An FEM-DEM numerical approach to simulate secondary fragmentation’, Computer Methods and Recent Advances in Geomechanics: Proceedings of the 14th International Conference of International Association for Computer Methods and Recent Advances in Geomechanics, Taylor & Francis Books Ltd, Milton Park,
pp. 1623–1628
Elmo, D & Stead, D 2021, ‘The role of behavioural factors and cognitive biases in rock engineering’, Rock Mechanics and Rock Engineering, vol. 54, no. 1, pp. 1–20,
Elmo, D, Mitelman, A & Yang, B 2022, ‘An examination of rock engineering knowledge through a philosophical lens’, Geosciences, vol. 12, no. 174,
Hoek, E 1999, ‘Putting numbers to geology—an engineer's viewpoint’, Quarterly Journal of Engineering Geology and Hydrogeology, vol. 32, no. 1, pp. 1–19.
Mitelman, A 2020, Derivation of an Equivalent Boundary Method for Ground Interaction Problems, PhD thesis (unpublished), The University of British Columbia, Vancouver.
Owen, DRJ, Feng, YT, de Souza Neto, EA, Cottrell, MG, Wang, F, Andrade Pires, FM & Yu, J 2004, ‘The modelling of multi-fracturing solids and particulate media’, International Journal for Numerical Methods in Engineering, vol. 60. pp. 317–339.
Pine, RJ, Owen, DRJ, Coggan, JS & Rance, JM 2007, ‘A new discrete modelling approach for rock masses’, Geotechnique, vol. 57, no. 9, pp 757–766.
Rogers, S, Elmo, D, Webb, G & Catalan, A 2014, ‘Volumetric fracture intensity measurement for improved rock mass characterisation and fragmentation assessment in block caving operations’, Rock Mechanics and Rock Engineering, vol. 48, no. 2,
pp. 633–649.
Sainsbury, D, Sainsbury, B, Board, M & Loring, D 2011, ‘Numerical back analysis of structurally controlled cave initiation at propagation at the Henderson Mine’, in AT Innacchione, GS Esterhuizen & AN Tutuncu (eds), Proceedings of the 45th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria.
Sainsbury, B, Sainsbury, D & Carroll, D 2018, 'Back-analysis of PC1 cave propagation and subsidence behaviour at the Cadia East mine', 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. 167–178,
Shapka-Fels, T & Elmo, D 2022, ‘Numerical modelling challenges in rock engineering with special consideration of open pit to underground mine interaction’, Geosciences, vol. 12, no. 5,
Vyazmensky, A 2008, Numerical Modelling of Surface Subsidence Associated with Block Cave Mining Using a Finite Element/Discrete Element Approach, PhD thesis, Simon Fraser University, Burnaby.
Vyazmensky, A, Elmo, D & Stead, D 2009a, ‘Role of Rock mass fabric and faulting in the development of block caving induced subsidence’, Rock Mechanics and Rock Engineering, vol. 43,
Vyazmensky, A, Stead, D, Elmo, D & Moss, A 2009b, ‘Numerical analysis of block caving-induced instability in large open pit slopes: a finite element/discrete element approach’, Rock Mechanics and Rock Engineering, vol. 43, no. 1, pp. 21–39.




© Copyright 2022, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to repository-acg@uwa.edu.au