Fuenzalida, MA, Orrego, C, Ghazvinian, E & Pierce, ME 2022, 'Application of rock mass strength scale effect at Cadia East mine', in Y Potvin (ed.), Caving 2022: Proceedings of the Fifth International Conference on Block and Sublevel Caving
, Australian Centre for Geomechanics, Perth, pp. 951-962, https://doi.org/10.36487/ACG_repo/2205_65
The relevance of the scale effect when considering rock mass strength in different aspects of mine design in a caving mine is critical. A proper understanding of rock mass strength at different scales is required to appropriately forecast cave growth, subsidence, infrastructure and footprint stability.
Evidence of rock mass strength scale effect is studied at Cadia East mine by performing a back-analysis of 1) the large-scale subsidence, and 2) stability performance of a crusher chamber.
A methodology to account for the scale effect is proposed by fitting a power-law function to the results of the back-analysis. The fitted equation is then verified based on an improved rock mass knowledge derived from a recent systematic point load test campaign.
The proposed approach serves as a framework to incorporate the scale effect in the rock mass strength in the design for future panels at Cadia East mine.
Keywords: scale effect, rock mass strength, subsidence, stability, crusher chamber
Bieniawski, ZT & Van Heerden, WL 1975, ‘The significance of in situ tests on large rock specimens’, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, vol. 12, issue 4, pp. 101–113.
Board, M & Pierce, M 2009, ‘A review of recent experience in modelling of caving’, International Workshop on Numerical Modelling for Underground Mine Excavation Design, June 28 2009, Asheville, in conjunction with the 43rd US Rock Mechanics Symposium.
Cavieres, P, Gaete, S, Lorig, L & Gómez, P 2003, ‘Three-Dimensional analysis of fracturing limits induced by large scale underground mining at El Teniente Mine’, in PJ Culligan, HH Einstein & AJ Whittle (eds), Proceedings of the 39th U.S. Rock Mechanics Symposium, Verlag Glückauf, Essen, pp. 893–900.
Ghazvinian, E, Fuenzalida, M, Orrego, C & Pierce, M 2020, ‘Back analysis of cave propagation and subsidence at Cadia East mine’,
in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining, University of Chile, Santiago, pp. 535–550,
Hoek, E & Brown, ET 1980, Underground Excavations in Rock, Institution of Mining and Metallurgy, London
Holliday, JR, Wilson, AJ, Blevin, PL, Tedder, IJ, Dunham, PD & Pfitzner, M 2002, orphyry gold–copper mineralisation in the Cadia district, eastern Lachlan Fold Belt, New South Wales, and its relationship to shoshonitic magmatism’, Mineralium Deposita, vol. 37, pp. 100–116,
Itasca Consulting Group, Inc. 2019, FLAC3D — Fast Lagrangian Analysis of Continua in Three Dimensions, version 7, computer software, Itasca, Minneapolis.
ISRM 2007, The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring: 1974-2006, R Ulusay
& JA Hudson (eds), International Society for Rock Mechanics, Lisbon.
Lee, MD 1992, The Angles of Friction of Granular Fills, PhD thesis, University of Cambridge, Cambridge.
Newcrest Mining Limited 2021, Cadia PC1-2 Pre-feasibility Study Delivers Attractive Returns,
Pierce, M, Gaida, M & Degagne, D 2009, ‘Estimation of rock block strength, in M Diederichs & G Grasselii (eds), RockEng09: Proceedings of the 3rd Canada-US Rock Mechanics Symposium & 20th Canadian Rock Mechanics Sympsium, Canadian Rock Mechanics Association, Toronto.
Pierce, M, O’Connor, C, Sainsbury, D, Lavoie, T, Garcia, X & Board, M 2011, Predictions of caving and infrastructure stability in support of the feasibility study for panel caving at Oyu Tolgoi, Hugo North, Lift 1, Itasca internal report ICG11-2619-P03-51.
Sainsbury, BL 2012, A Model for Cave Propagation and Subsidence Assessment in Jointed Rock Masses, PhD thesis, The University of New South Wales, Sydney.
Sjöberg, J 1999, Analysis of Large Scale Rock Slopes, PhD thesis, Luleå University of Technology, Luleå.
Yoshinaka, R, Osada, M, Park, H, Sasaki, T & Sasaki, K 2008, ‘Practical determination of mechanical design parameters of intact rock considering scale effect‘, Engineering Geology, vol. 96, pp. 173–186.