Authors: Koosmen, K; Serati, M; Craig, B

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Koosmen, K, Serati, M & Craig, B 2023, 'Multistage triaxial testing of intact rock: volumetric strain-based methods applied to rock slope design', in PM Dight (ed.), SSIM 2023: Third International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, pp. 343-358,

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Triaxial testing of intact rock is commonly undertaken to provide input parameters for rock slope design. Multistage triaxial tests offer economies in terms of time, sample quantities and costs, and for these reasons have found commonplace in engineering practice. Volumetric strain-based methods are sometimes employed for multistage testing to minimise damage accumulation in early test stages. This is done by (1) terminating early test stages at volumetric strain reversal, (2) straining the final stage until failure occurs, then (3) inferring a peak stress for the earlier stages based on a correction factor derived from the final stage. This paper provides a review of multistage triaxial testing along with fundamental rock mechanics theories that underpin the volumetric strain-based multistage testing method. Results from single and multistage tests are then used to demonstrate possible errors that may result if multistage tests are conducted over a range of stresses where compressive failure of intact rock is controlled by different failure mechanisms. Finally, some examples and discussion are provided to demonstrate the possible impact that these errors may have on rock slope stability assessments.

Keywords: intact rock strength, triaxial testing, multistage methods, rock fracture mechanics

Brace WF, Paulding, BW & Scholz, C 1966, ‘Dilatancy in the fracture of crystalline rocks’, Journal of Geophysical Research, vol. 71, no. 16, pp. 3939–3953.
Bieniawski, ZT 1978 ‘Determining rock mass deformability: experience from case histories’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, vol. 15, no.5, pp 237–247.
Diederichs, MS, Carter, T & Martin, D 2009, ‘Practical rock spall prediction in tunnels’, in Proceedings of the International Tunnelling Association World Tunnel Congress, pp. 1–8.
Eberhardt, E, Stead, D, Stimpson, B & Read, RS 1998, ‘Identifying crack initiation and propagation thresholds in brittle rock’, Canadian Geotechnical Journal, vol. 35, no. 2, pp. 222–233.
Einstein, EW & Dershowitz, WS 1990, ‘Tensile and shear fracturing in predominantly compressive stress fields – a review’, Engineering Geology, vol. 29, pp 149–172.
Gramberg, J 1989, A Non-Conventional Review on Rock Mechanics and Fracture Mechanics, CRC Press, Boca Raton.
Griffith, AA 1920, ‘The phenomena of rupture and flow in solids’, The Philosophical Transactions of the Royal Society of London, vol. 221, pp. 163–198.
Griffith, AA 1924, ‘The theory of rupture’, in CB Biezeno & JM Burgers (eds), Proceedings of the First International Congress for Applied Mechanics, Delft Tech, pp 55–63.
Gupta, V & Bergstrom, JS 1998, ‘Compressive failure of rocks by shear faulting’, Journal of Geophysical Research: Solid Earth, vol. 110, no. B10, pp. 23875–23895 .
Hoek, E 1965, Rock Fracture Under Static Stress Conditions, report for Council for Scientific and Industrial Research, MEG 383, Pretoria.
Hoek, E & Brown, ET 1980a, ‘Empirical strength criterion for rock masses’, Journal of the Geotechnical Engineering Division, ASCE, vol. 106, no. 9, pp 1013–1035.
Hoek, E & Brown, ET 1980b, Underground Excavations in Rock, Institute of Mining and Metallurgy, London.
Hoek, E 1983, ‘The strength of jointed rock masses’, Geotechnique, vol. 33, no. 3, pp. 187–222.
Hoek, E, Kaiser, PK & Bawden, WF 1995, Support of Underground Excavation in Hard Rock, A.A. Balkema, Rotterdam.
Hoek, E & Brown, ET 2018, ‘The Hoek-Brown failure criterion and GSI – 2018 edition’, Journal of Rock Mechanics and Geotechnical Engineering, vol. 11, is. 3, pp.445–463.
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. 278–300.
Horii, H & Nemat-Nasser, S 1985, ‘Compression-induced microcrack growth in brittle solids - axial splitting and shear failure’, Journal of Geophysical Research, vol. 90, no. B4, pp. 3105–3125.
Kaiser, PK & Kim, BH 2014, ‘Characterization of strength of intact brittle rock considering confinement-dependent failure processes’, Rock Mechanics and Rock Engineering, vol. 48, pp. 107–119.
Kovari, K & Tisa, A 1975, ‘Multiple failure state and strain controlled triaxial tests’, Rock Mechanics, vol. 7, pp. 17–33.
Lajtai, EZ 1974, ‘Brittle fracture in compression’, International Journal of Fracture, vol. 10, pp. 525–536.
Lockner, DA, Moore, DE & Reches, Z 1992, ‘Microcrack interaction leading to shear failure’, paper presented at the 33rd U.S. Symposium on Rock Mechanics, Santa Fe, New Mexico.
Martin, CD 1993, Strength of Massive Lac du Bonnet Granite Around Underground Openings, PhD thesis, University of Manitoba, Winnipeg.
Martin, CD & Chandler, NA 1994, ‘The progressive fracture of Lac du Bonnet granite’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, vol. 31, no. 6, pp. 643–659.
Martin, CD 1997, ‘The effect of cohesion loss and stress path on brittle rock strength’, Canadian Geotechnical Journal, vol. 34, no. 5, pp.698–725.
Mogi, K 1966, ‘Pressure dependence of rock strength and transition from brittle fracture to ductile flow’, Bulletin Earthquake Research Institute, vol. 44, no 215–232.
Mostyn, GR & Douglas, KJ 2000, ‘Strength of intact rock and rock masses’, paper presented at the GeoEng2000 Conference, Melbourne.
Mutaz, E, Serati, M, Bahaaddini, M & Williams, B 2021, ‘On the evolution of crack initiation stress threshold’, paper presented at The 55th U.S. Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria.
Nicksiar, M & Martin, CD 2013, ‘Crack initiation stress in low porosity crystalline and sedimentary rocks’, Engineering Geology, vol. 154, pp. 64–76.
Orilogi, E 2019, Evaluating Volumetric Strain as a Predictor of Yield and Peak Strength for the Multistage Triaxial Test: A Case Study with Utah Coal Specimens, MSc thesis, Montana Technological University, Butte.
Pagoulatos, A 2004, Evaluation of Multistage Triaxial Testing on Berea Sandstone, MSc thesis, The University of Oklahoma, Norman.
Taheri, A, Zhang, Y & Munoz, H 2020, ‘Performance of rock crack stress thresholds determination criteria and investigating strength and confining pressure effects’, Construction and Building Materials, vol. 243.
Tang, C & Hudson, JA 2011, Rock Failure Mechanisms, Taylor & Francis, London.
Tapponnier, P & Brace, WF 1976, ‘Development of stress-induced microcracks in Westerly granite’, International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, vol. 13, pp. 103–112.
Venter, J, Hammah, ECF & Purvis, C 2019, ‘New revelations in intact rock strength through automated triaxial testing’, paper presented at the 53rd U.S. Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, Alexandria.

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