Authors: Sullivan, TD


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Sullivan, TD 2013, 'Global slope performance index', in PM Dight (ed.), Slope Stability 2013: Proceedings of the 2013 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 55-80,

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The evaluation of the performance and risk of excavated slopes is a complex esoteric task. Slope designers are always faced with gaps and uncertainties and in many cases the conditions as exposed are significantly different to the design predictions. In theory these issues may be addressed with detailed, rigorous investigations, analysis and models. But experience shows that even this approach is not always successful and surprises occur. The paper presents a simple empirical system for predicting the current and future performance of excavated slopes. The system is the result of decades of experience with the design and evaluation of 100s of slopes excavated for both mining and civil purposes. The examples include a very wide range of slope heights, slope angles, environments and material types. The experience also covers the full spectrum of operational performance, from stable slopes, to complete collapse. In very simple terms three principal elements contribute to the stability of excavated slopes; intact strength, geological structure and groundwater. The Global Slope Performance Index (GSPI) is based on these three elements divided into five indices. These indices are each rated with a linear numerical scale and then combined into a simple algorithm, the GSPI. The index has been benchmarked against actual slope performances and demonstrated by statistical analysis, which allows the likelihood of different slope performances and risk to be determined based on the Global Slope Performance Index.

Attewell, P.B. and Farmer, I.W. (1975) Principles of Engineering Geology, John Wiley & Sons, New York.
AusIMM (1995) Field Geologists Manual, Monograph 9.
Australian Standards (1993) Geotechnical site investigations, AS 1726–1993.
Bieniawski, Z.T. (1976) Rock mass classification in rock engineering, in Proceedings Symposium on Exploration for Rock Engineering, Z.T. Bieniawski (ed), 1–5 November 1976, Johannesburg, South Africa, Balkema, Rotterdam, pp. 97–107.
Bieniawski, Z.T. (1989) Engineering rock mass classifications, John Wiley & Sons, New York.
CANMET (1977) Canada Centre for Mineral and Energy Technology, Pit slope manual, chapter 2 structural geology, G. Herget (ed), CANMET REPORT, pp. 88.
Chen, Z. (1995) Recent developments in slope stability analysis, in Proceedings 8th International Congress on Rock Mechanics, Vol. 3, 25–30 September 1995, Tokyo, Japan, International Society for Rock Mechanics, pp. 1,041–1,048.
Davis, G.H. (1984) Structural geology of rocks and regions, John Wiley & Sons, New York.
Dawes, R.M. (1979) The robust beauty of improper linear models in decision making, American Psychologist, 34, pp. 571–582.
Douglas, K.J. (2002) The shear strength of rock masses, PhD thesis, The University of New South Wales, Kensington, Australia.
Driscoll, R. and Simpson, B. (2001) EN1997 Eurocode 7: Geotechnical design, ICE – Civil Engineering, Thomas Telford Ltd, Vol. 144, Issue 6, pp. 49–54.
Geological Society, Engineering Geology Working Group (1977) The description of rock masses for engineering purposes, Quarterly Journal of Engineering Geology and Hydrogeology, Geological Society of London, Vol. 10, pp. 355–388.
Haines, A. and Terbrugge, P.J. (1991) Preliminary estimation of rock slope stability using rock mass classification systems, in Proceedings 7th International Society Rock Mechanics, 16–20 September 1991, Aachen, Germany, International Society for Rock Mechanics, Vol. 2, pp. 887–892.
Hartford, D.N.D. (1998) This dam risk business – The challenge of implementation – managing the risks of risk assessment, ANCOLD Bulletin, Australian National Committee on Large Dams, No. 110.
Hoek, E., Kaiser, P.K. and Bawden, W.F. (1995) Support of Underground Excavations in Hard Rock, Balkema, Rotterdam.
ISRM (1978) Suggested methods for the quantitative description of discontinuities in rock masses, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, Elsevier, Vol. 15, pp. 319–368.
ISRM (2007) The complete ISRM suggested methods for rock categorisation, testing and monitoring: 1974–2006, R. Ulusay and J.A. Hudson (eds), International Society for Rock Mechanics Turkish national Group, Ankara, Turkey.
Kahneman, D. (2011) Thinking, fast and slow, Penguin, London.
Laubscher, D.H. (1977) Geomechanics classification of jointed rock masses – mining applications, Transactions of the Institution of Mining and Metallurgy, Section A, Mining Industry, Vol. 86 (Jan), pp. A1–A8.
Laubscher, D.H. (1990) A geomechanics classification system for the rating of rock mass in mine design, Journal of the South African Institute of Mining and Metallurgy, Southern African Institute of Mining and Metallurgy, Vol. 90 (10), pp. 257–273.
Lin, Y. (1998) An introduction of the Chinese standard for engineering classification of rock mass, Advances in Rock Mechanics, World Scientific Publishing Co., Singapore, pp. 317–327.
Marinos, P. and Hoek, E. (2000) GSI: A geologically friendly tool for rock mass strength estimation, in Proceedings GeoEng 2000 Conference, 19–24 November 2000, Melbourne, Australia, Technomic Publishing Company, Lancaster, Vol. 1, pp. 1422−1440.
McMahon, B.K. (1985) E.H. Davis Memorial Lecture: geotechnical design in the face of uncertainty, Australian Geomechanics Journal, Australian Geomechanics Society, Issue 10, pp. 7–19.
Orr, C.M. (1992) Assessment of rock slope stability using the rock mass rating (RMR) system, The AusIMM Proceedings, Australasian Institute of Mining and Metallurgy, Carlton, Vol. 297(2), pp. 25-29.
Robertson, A.M. (1988) Estimating weak rock strength, SME Annual Meeting, Tuscon, Arizona, Society of Mining Engineers, Preprint No. 88–145, pp. 1–5.
Romana, M. (1985) New adjustment ratings for application of Bieniawski classification to slopes, in Proceedings International Symposium on the Role of Rock Mechanics, 2–4 September 1985, Zacatecas, Mexico, International Society for Rock Mechanics, Lisbon, pp. 49–53.
Royal Society (1992) Science, policy and risk, Royal Society Publishing, London.
Selby, M.J. (1980) A rock mass strength classification for geomorphic purposes: with tests from Antarctica and New Zealand, Zeitschrift fur Geomorphologie, N.F., Schweizerbart Science Publishers, Vol. 24 (1), pp. 31–51.
Sullivan, T.D. (1994) Mine slope design – The chances of getting the answer right and the risk of getting it wrong, in Proceedings 4th Large Open Pit Mining Conference, 5–9 September 1994, Perth, Australia, South African Institute of Mining and Metallurgy, Johannesburg.
Sullivan, T.D. (2006) Pit slope design and risk – A view of the current state of the art, in Proceedings Symposium Series S44, Stability of rock slopes in open pit mining and civil engineering situations, 3–6 April 2006, Johannesburg, South Africa, South African Institute of Mining and Metallurgy, Cape Town.
Sullivan, T.D. (2007) Hydromechanical coupling and pit slope movements, Keynote Lecture, in Proceedings International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering (Slope07), Y. Potvin (ed), 12–14 September 2007, Perth, Australia, Australian Centre for Geomechanics, Perth, pp. 3–43.
Terzaghi, K. and Peck, R.B. (1967) Soil mechanics in engineering practice, Second Edition, John Wiley & Sons, New York.
Ünal, E. (1996) Modified rock mass classification: M-RMR system, milestones in rock engineering, The Bieniawski Jubilee Collection, Balkema, Rotterdam, pp 203–223.
Wyllie, D.C. and Mah, C.W. (2004) Rock Slope Engineering: Civil and Mining, 4th edition, Spoon Press.

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