Carter, TG, Rogers, SF, Taylor, JJL & Smith, J 2015, 'Unravelling structural fabric — a necessity for realistic rock mass characterisation for deep mine design', in Y Potvin (ed.), Design Methods 2015: Proceedings of the International Seminar on Design Methods in Underground Mining
, Australian Centre for Geomechanics, Perth, pp. 317-338, https://doi.org/10.36487/ACG_rep/1511_19_Carter
In recent years, there has been a spate of quite unexpected major failures within surface and underground mines that have significantly compromised mine stability and resulted in sustained loss of production. In the majority of these cases, evidence suggests that incipient, weak, generally incoherent structural fabric within the rock mass played a significant role in influencing the failure development. With the trend towards underground mines going ever deeper, and many of the large open pits transitioning to block cave operations, more focus is needed on gaining better structural geological understanding of incipient rock mass fabric within and outside the mining block so that such failure risks can be minimised.
Current trends towards mine scale quantification of rock mass characteristics and development of local and regional scale discrete fracture network simulations, as basis for generation of synthetic rock mass models based on rigorous quantification of geological fabric assessments, is allowing better appreciation of the variability within a rock mass. However, comprehensive understanding of key elements of the geological fabric is often missing. This can lead, in worst case scenarios, to situations when the resulting models cannot be expected to capture the controlling mechanisms.
This paper presents several structural geology techniques that are not widely known, or even commonly applied, either for large deep open pit design studies or for deep high stress underground mining. These techniques have merit for aiding risk minimisation for deep excavation through improved insight.
Guidelines are provided for using fault striae data and applying stress inversion, slip tendency and critical stress evaluation approaches for advancing understanding of past and present day stress states — both key factors important to establishing the current stability state of major geologic structures transecting or bounding large surface or underground mining extraction blocks. Some techniques for estimating likely risk for inducing adverse slip on incipient geologic structures, potentially affected by mining, are also explored in the final sections of the paper.
Allmendinger, RW, Gephart, JW & Marrett, RA 1989, ‘Notes on fault slip analysis’, Proceedings of the Geological Society of America Short Course on Quantitative Interpretation of Joints and Faults, Cornell University, Ithaca, NY, viewed 1 July 2015, www.geo.cornell.edu/pub/rwa/GSAFaults89.pdf
Anderson, EM 1951, The dynamics of faulting, 2nd edn, Oliver & Boyd, Edinburgh.
Angelier, J 1994, ‘Fault slip analysis and palaeostress reconstruction’ in PL Hancock (ed.), Continental deformation, Pergamon Press, Oxford, pp. 53-100.
Angelier, J & Mechler, P 1977, ‘Sur une méthode graphique de recherche des contraintes principales également utilisable en tectonique et en séismologie: la méthode des dièdres droits’, Bulletin de la Societe Geologique de France, vol. 19,
pp. 1309-1318. [In French]
Arthaud, F 1969 ‘Méthode de détermination graphique des directions de raccourcissement, ďallongement et intermédiaire ďune population de failles’, Bulletin de la Societe Geologique de France, vol. 11, pp. 729-737. [In French]
Badgley, PC 1959, Structural methods for the exploration geologist, Harper, New York, NY.
Barton, CA, Zoback, M & Moos, D 1995, ‘Fluid flow along potentially active faults in crystalline rock’, Geology, vol. 23, no. 8,
Barton, N & Bandis, S 1982, ‘Effects of block size on the shear behaviour of jointed rock’, in RE Goodman and FE Heuze (eds), Proceedings of the 23rd US Symposium on Rock Mechanics (USRMS), American Rock Mechanics Association, Minneapolis, MN, pp. 739-760.
Barton, N, Lien, R & Lunde, J 1974, ‘Engineering classification of rock masses for design of tunnel support’, Rock Mechanics and Rock Engineering, vol. 6, no. 4, pp. 189-236.
Bieniawski, ZT 1973, ‘Engineering classification of jointed rock masses’, Transactions of the South African Institution of Civil Engineers, vol. 15, no. 12, pp. 335-344.
Bieniawski, ZT 1989, Engineering rock mass classifications, John Wiley & Sons, New York.
Board, M 1994, ‘Numerical examination of mining-induced seismicity’ PhD thesis, University of Minnesota.
Bott, MHP 1959, ‘The mechanisms of oblique slip faulting’, Geological Magazine, vol. 96, pp. 109-117.
Carter, TG 1992, ‘Prediction and uncertainties in geological engineering and rock mass characterization assessment’, Proceedings of the 4th Italian Rock Mechanics Conference, pp. 1.1-1.22.
Carter, TG 2010, ‘Applicability of classifications for tunnelling - valuable for improving insight, but problematic for contractual support definition or final design’, Proceedings of the World Tunnelling Conference (WTC 2010) and the 36th ITA Congress, section 6c, 8 p.
Carter, TG 2011 ‘Himalayan ground conditions challenge innovation for successful TBM tunnelling’, Proceedings of the Hydrovision India 2011 Conference, Golder Associates, Toronto, ON, 20 p.
Carter, TG 2015a ‘On increasing reliance on numerical modelling and synthetic data in rock engineering’, Proceedings of the 13th International Congress on Rock Mechanics, 17 p.
Carter, TG 2015b, ‘Some geological characterization techniques for assessing fault influence on deep excavations’, Proceedings of the 13th International Congress on Rock Mechanics, 11 p.
Carter, TG & Bewick, RP 2011, Structural geological guidelines for aiding characterization of deep mining fault behaviour, Centre of Excellence in Mining Innovation, Sudbury.
Carter, TG & Valley, BC 2013, ‘Application of fault stability analysis techniques for design of deep engineering projects’, Proceedings of the 47th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Minneapolis, MN, 12 p.
Castro, LMC, Carter, TG & Lightfoot, N 2009, ‘Investigating factors influencing fault-slip in seismically active structures,
in M Diederichs & G Grasselli (eds), Proceedings of the Third Canada-US Rock Mechanics Symposium and the 20th Canadian Rock Mechanics Symposium (RockEng09), 10 p.
Célérier, B, Etchecopar, A, Bergerat, F, Vergely, P, Arthaud, F & Laurent, P 2012, ‘Inferring stress from faulting: from early concepts to inverse methods’, Tectonophysics, vol. 581, pp. 206-219.
Cronin, VS 2010, A primer on focal mechanism solutions for geologists (Updated), viewed 1 August 2015,
Frohlich, C 2001, ‘Display and quantitative assessment of distributions of earthquake focal mechanisms’, Geophysical Journal International, vol. 144, no. 2, pp. 300-308.
Hoek, E & Brown, ET 1980a, ‘Empirical strength criterion for rock masses’, Journal of the Geotechnical Engineering Division,
vol. 106, no. 9, pp. 1013-1035.
Hoek, E & Brown, ET 1980b, Underground excavations in rock, Institution of Mining and Metallurgy, London.
Hoek, E & Martin, CD 2014, ‘Fracture initiation and propagation in intact rock – a review’, Journal of Rock Mechanics and Geotechnical Engineering, vol. 6, no. 4, pp. 287-300.
Hoek, E & Marinos, P 2000, ‘GSI: a geologically friendly tool for rock mass strength estimation’, Proceedings of the GeoEng 2000 Conference, pp. 1422-1442.
Hoek, E, Carter, TG & Diederichs, MS 2013, ‘Quantification of the geological strength index chart’, Proceedings of the 47th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Minneapolis, MN, 8 p.
Itasca Consulting Group, Inc. 2015, FLAC3D: Fast Lagrangian Analysis of Continua in 3 Dimensions, versions 7-5, Itasca Consulting Group, Inc., Minneapolis, MN,
Jackson, J & McKenzie, D 1988, ‘The relationship between plate motions and seismic moment tensors, and the rates of active deformation in the Mediterranean and Middle East’, Geophysical Journal, vol. 93, pp. 45-73.
Jaeger, JC & Cook, NGW 1984, ‘Fundamentals of rock mechanics, 3rd edn, Chapman & Hall, London.
Kaiser, PK, Amman, F & Bewick, RP 2015, ‘Overcoming challenges of rock mass characterization for underground construction in deep mines’, Proceedings of the 13th International Congress of Rock Mechanics, 14 p.
Laubscher, DH 1977, ‘Geomechanics classification of jointed rock masses – mining applications’, Transactions of the Institute of Mining and Metallurgy, vol. 86, pp. 1-8.
Lisle, R 1987, ‘Principal stress orientations from faults: an additional constraint Ann’, Tectonicae, vol. 1, pp. 155-158.
Lisle, R 2013, ‘A critical look at the Wallace-Bott hypothesis in fault-slip analysis’, Bulletin of the Société Géologique de France,
vol. 184, no. 4-5 pp. 299-306.
Lisle, R, Orife, T & Arlegui, L 2001, ‘A stress inversion method requiring only fault slip sense’, Journal of Geophysical Research, vol. 106, no. B2, pp. 2281-2289.
Marinos, V, Marinos, P & Hoek, E 2005, ‘The geological strength index: applications and limitations’, Bulletin of Engineering Geology and the Environment, vol. 64, no. 1, pp. 55-65.
Mathews, KE, Hoek, E, Wyllie, DC & Stewart, S 1981, Prediction of stable excavation spans for mining at depths below 1,000 metres in hard rock / Golder Associates, CANMET Library & Documentation Services Division, Vancouver.
Morris, A, Ferrill, DA & Henderson, DB 1996, ‘Slip-tendency analysis and fault reactivation’, Geology, vol. 24, no. 3, pp. 275-278.
Palmström, A 2000, ‘Recent developments in rock support estimates by the RMi’, Journal of Rock Mechanics and Tunnelling Technology, vol. 6, no. 1, pp. 1-19.
Palmström, A 2005, ‘Measurements of and correlations between block size and rock quality designation (RQD)’, Tunnels and Underground Space Technology, vol. 20, pp. 362-377.
Palmström, A 2009, Combining the RMR, Q, and RMi classification systems, www.rockmass.net, 25 p.
Pollard, DD & Fletcher, RC 2005, Fundamentals of structural geology, Cambridge University Press, Cambridge.
Potvin, Y, Hudyma, M & Miller, HDS 1989, ‘Design guidelines for open stope support’, Bulletin of the Canadian Institute of Mining and Metallurgy, vol. 82, no. 926, pp. 53-62.
Ramsay, JG & Lisle, RJ 2000, ‘Fault slip analysis and stress tensor calculation’, The techniques of modern structural geology: applications of continuum mechanics in structural geology, Academic Press, London, vol. 3, pp. 785-810.
Reiter, F & Acs, P 2002, Tectonics FP software for structural geology, version 1.6,
Ritz, JF 1994, ‘Determining the slip vector by graphical construction – use of a simplified representation of the stress tensor, Journal of Structural Geology, vol. 16, no. 5, pp. 737-741.
Robertson, AM 1988, ‘Estimating weak rock strength’, Proceedings of the SME Annual Meeting, Society for Mining, Metallurgy & Exploration, Englewood, CO, preprint no. 88-145, 5 p.
Rocscience 2014, Examine2D – 2-Dimensional plane strain boundary element program for elastic stress analysis of underground excavations software with slip tendency update, version 8.0, Rocscience, Toronto, ON,
Romana, M 1985, ‘New adjustment rating for application of the Bieniawski classification to slopes’, Proceedings of the International Symposium on Role of Rock Mechanics, International Society for Rock Mechanics, Salzburg, pp. 49-53.
Romana, M, Serón, JB & Montalar, E 2003, ‘SMR Geomechanics classification: Application, experience and validation ISRM 2003–Technology roadmap for rock mechanics’, Journal of the Southern African Institute of Mining and Metallurgy, pp. 981-984.
Sainsbury, B, Pierce, M & Mas Ivars, D 2008, ‘Analysis of Caving Behaviour Using a Synthetic Rock Mass —Ubiquitous Joint Rock Mass Modelling Technique, in Y Potvin, J Carter, A Dyskin & R Jeffrey (eds), Proceedings of the First Southern Hemisphere International Rock Mechanics Symposium (SHIRMS), vol. 1 – Mining and Civil, Australian Centre for Geomechanics, Perth, pp. 243-254.
Wallace, RE 1951, ‘Geometry of shearing stress and relation to faulting’, The Journal of Geology, vol. 59, no. 2, pp. 118-130.
Wiles, T 2014, ‘Three ways to assess mining-induced fault instability using numerical modelling’, Proceedings of the 6th South African Rock Engineering Symposium (SARES), The Southern African Institute of Mining and Metallurgy, Johannesburg, 13 p.
Worum, G, van Wees, J-D, Boda, G, van Balen, RT, Cloetingh, S & Pagnier, H 2004, ‘Slip tendency analysis as a tool to constrain fault reactivation: a numerical approach applied to three-dimensional fault models in the Roer Valley rift system (southeast Netherlands)’, Journal of Geophysical Research, vol. 109, 16 p.
Žalohar, J 2009, T-TECTO 3.0 professional integrated software for structural analysis of fault-slip data, University of Ljubljana, Ljubljana.
Žalohar, J 2012, ‘Cosserat analysis of interactions between intersecting faults; the wedge faulting’, Journal of Structural Geology, vol. 37, pp. 105-123.
Žalohar, J & Vrabec, M 2007, ‘Paleostress analysis of heterogeneous fault-slip data: the Gauss method’, Journal of Structural Geology, vol. 29, pp. 1798-1810.