Step-Path method — impact of defect occurrence, cut-off and length on shear strength in rock slopes

Authors: Baczynski, NRP

DOI https://doi.org/10.36487/ACG_rep/1604_14_Baczynski

Cite As:
Baczynski, NRP 2016, 'Step-Path method — impact of defect occurrence, cut-off and length on shear strength in rock slopes', in PM Dight (ed.), APSSIM 2016: Proceedings of the First Asia Pacific Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, pp. 271-287, https://doi.org/10.36487/ACG_rep/1604_14_Baczynski

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
Examples of statistical models for geological defect attributes are presented. Whilst data collection errors can occur for all attributes, the factors specifically influencing defect length measurements are examined in more detail. Mapped lengths may underestimate actual lengths by 60 to 80%. Hoek–Brown and Step-Path methods are used to estimate shear strength of failure paths through rock slopes. Both methods are compared. For the inputs considered, Step-Path method may yield shear strength results that are up to 40% lower than Hoek–Brown results. Inputs influencing Step-Path results are examined. Implications of Hoek–Brown and Step-Path results for pit slope design Factors of Safety are discussed.

Keywords: factors impacting defect length models, length estimation errors, Step-Path method, errors in rock mass strength, slope stability

References:
Baczynski, NRP 1980, ‘Rock mass characterization and its application to assessment of unsupported underground openings’, PhD thesis, dated Nov 1980, Department of Mining & Metallurgy, University of Melbourne, Australia, p. 233.
Baczynski, NRP 2000, ‘STEPSIM4 Step-Path method for slope risks’, in Proceedings for GeoEng 2000: International Conference on Geotechnical and Geological Engineering, Melbourne, vol. 2, p. 86.
Barton, N 1976, ‘The shear strength of rock and rock joints’, International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, vol. 13, pp. 1–24.
Bieniawski, ZT 1989, Engineering Rock Mass Classifications, John Wiley & Sons, p. 251.
Carvalho, JL, Carter, TG & Diederichs, MS 2007, ‘An approach for prediction of strength and post yield behaviour for rock masses of low intact strength’, in Rock Mechanics: Meeting Society's Challenges and Demands, pp. 249–257.
Hoek, E & Brown, ET 1980a, ‘Empirical strength criterion for rock masses’, Journal of the Geotechnical Engineering Division, ASCE, vol. 106, no. GT9, pp. 1013–1035.
Hoek, E & Brown, ET 1980b, Underground Excavations in Rock, London Institution of Mining and Metallurgy.
Jennings, JE 1970, ‘A mathematical theory for the calculation of the stability of slopes in opencast mines’, in Proceedings of Symposium on the Theoretical Background to the Planning of Open Pit Mines, Johannesburg, pp. 87–102.
Little, LN, Cortes, JP & Baczynski, NR 1999, Risk-based slope design optimisation study for the Ok Tedi copper-gold mine: Volume 5: Geotechnical models and failure modes, internal report dated 30 Aug 1999, Ok Tedi Mining Limited, Mine Technical Services Department, Geotechnical Engineering Section, p. 108 & Appendices A to F.
McMahon, BK 1971, ‘Statistical methods for the design of rock slopes’, in Proceedings of the First Australia-New Zealand Conference on Geomechanics’, vol. 1, pp. 314–321.
McMahon, BK 1974, ‘Design of rock slopes against sliding on pre-existing fractures’, in Proceedings of the 3rd Congress of the International Society for Rock Mechanics, National Academy of Sciences, Washington DC, vol. IIB, pp. 803–808.
McMahon, BK 1979, ‘Report to Bougainville Copper Limited on slope design studies, Pan Hill’, McMahon Burgess & Yates, Sydney, internal report.
Read, JRL & Lye, GN 1983, ‘Pit slope design methods, Bougainville Copper Limited open cut’, in Proceedings of the 5th Congress of the International Society for Rock Mechanics, Rotterdam, Balkema, Melbourne, vol. 1, pp. C93–C98.




© Copyright 2024, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
View copyright/legal information
Please direct any queries or error reports to repository-acg@uwa.edu.au