Esterhuizen, GS, Bajpayee, TS, Murphy, MM & Ellenberger, JL 2013, 'Evaluation of the strength reduction method for US coal mine entry stability analysis', in Y Potvin & B Brady (eds), Proceedings of the Seventh International Symposium on Ground Support in Mining and Underground Construction
, Australian Centre for Geomechanics, Perth, pp. 373-385, https://doi.org/10.36487/ACG_rep/1304_24_Esterhuizen
The strength reduction method (SRM) can be used to calculate a stability factor of a proposed excavation through the use of well-calibrated numerical models. The method models the excavation and support system while the rock mass strength is reduced in stages until failure is indicated. The stability factor is expressed as the ratio of the expected rock mass strength to the rock mass strength that results in failure. Using the stability factor, various support alternatives can be compared and the impact of specific changes to the support system can be evaluated. Strength reduction analyses were conducted using calibrated models of coal mine entries in various geological settings. The calculated stability factors were validated against the empirically derived Coal Mine Roof Rating (CMRR) and the Analysis of Roof Bolt Systems (ARBS), which is based on observation and statistical analysis of roofbolt systems in US coal mines. The results showed that the stability factors estimated through the SRM capture the essence of the CMRR, indicating improved stability at higher CMRR values and also replicating details such as the effect of a strong bed in the roof and the effect of a weak overlying bed. A linear relationship was found between the stability factors calculated by the strength reduction method and the ARBS. The calculated stability factors for instrumented field sites fell within the expected range of values based on observed entry stability. It is concluded that the stability factors calculated by the strength reduction method provide a meaningful interpretation of overall excavation stability. The numerical model outputs can be used to evaluate the contribution of support elements, allowing optimisation of the support design.
Anon. (2011) FLAC3D Fast Lagrangian Analysis of Continua in 3 Dimensions, Itasca Consulting Group, Minneapolis, MN.
Diederichs, M.S., Lato, M., Hammah, R. and Quinn, P. (2007) Shear Strength Reduction (SSR) approach for slope stability analyses, in Proceedings 1st Canada-US Rock Mechanics Symposium, E. Eberhardt, D. Stead and T. Morrison (eds), 27–31 May 2007, Vancouver, Canada, Taylor & Francis, London, pp. 319–327.
Dolinar, D. (2003) Variation of Horizontal Stresses and Strains in Mines in Bedded Deposits in the Eastern and Midwestern United States, in Proceedings 22nd International Conference on Ground Control in Mining, S.S. Peng, C. Mark, A.W. Khair, and K. Heasley (eds), 6–7 August 2003, Morgantown, USA, pp. 178–185.
Esterhuizen, G.S. (2012) A Stability factor for Supported Mine Entries Based on Numerical Model Analysis, in Proceedings 31st International Conference on Ground Control in Mining, T. Barczak, S. Tadolini, D. Opfer, M. Thompson, D. Claudhill, B. Warnick and S.S. Peng (eds), 31 July to 2 August 2012, Morgantown, USA, 9 p.
Esterhuizen, G.S. and Bajpayee, T.S. (2012) Horizontal stress related failure in bedded mine roofs—insight from field observations and numerical models, in Proceedings 46th US Rock Mechanics/Geomechanics Symposium, A. Bobet (ed), 24–27 June 2012, Chicaco, USA, Paper No. 137, 10 p.
Gale, W.J. (1999) Experience of Field Measurement and Computer Simulation Methods of Pillar Design, in Proceedings Second International Workshop on Coal Pillar Mechanics and Design, J.M. Galvin, B. Hebblewhite and M.D. Salamon, June 1999, Pittsburgh, USA, Department of Health and Human Services, National Institute for Occupational Safety and Health, IC 9448, pp. 49–61.
Gale, W.J., Mark, C., Olyer, D. and Chen, J. (2004) Computer Simulation of Ground Behaviour and Rock Bolt Interaction at Emerald Mine, in Proceedings of the 23rd International Conference on Ground Control in Mining, S.S. Peng, C. Mark, G. Finfinger, S. Tadolini, A.W. Khair and K. Heasley (eds), 3–5 August 2004, Morgantown, USA, pp. 27–34.
Harr, M.E. (1987) Reliability Based Design in Civil Engineering, McGraw Hill, 290 p.
Hoek, E. (1991) When is a Design in Rock Engineering Acceptable? Leopold Muller Lecture, in Proceedings 7th International Congress on Rock Mechanics, W. Wittke (ed), 16–20 September 1991, Aachen, Germany, Balkema, Rotterdam, pp 1,485–1,497.
Hoek, E. and Brown, E.T. (1980) Underground Excavations in Rock, Institute of Mining and Metallurgy, London, 527 p.
Lawson, H., Zahl, E. and Whyatt, J. (2012) Ground Condition Mapping: A Case Study, in Proceedings 2012 SME Annual Meeting, 1922 February 2012, Seattle, USA, Society for Mining, Metallurgy, and Exploration, Inc., Littleton, USA, Preprint, 9 p.
Lorig, L. and Varona, P. (2000) Practical Slope Stability Analysis using Finite-Difference Codes, Slope Stability in Surface Mining, W.A. Hustrulid, M.K. Mc Carter and D.J.A. van Zyl (eds), Society for Mining Metallurgy and Exploration Inc., Littleton, USA, pp. 115–124.
Mark, C. and Gadde, M. (2008) Global Trends in Coal Mine Horizontal Stress Measurements, in Proceedings 27th International Conference on Ground Control in Mining, S.S. Peng, C. Mark, G. Finfinger, S. Tadolini, A.W. Khair, K. Heasley and Y. Luo (eds), 29–31 July, Morgantown, USA, pp. 319–331.
Mark, C., Molinda, G.M. and Barton, T.M. (2002) New Developments with the Coal Mine Roof Rating, in Proceedings 21st International Conference on Ground Control in Mining, S.S. Peng, C. Mark, A.W. Khair and K. Heasley (eds), 6–8 August 2002, Morgantown, USA, pp. 294–301.
Mark, C., Molinda, G.M. and Dolinar, D.R. (2001) Analysis of Roof Bolt Systems, in Proceedings 20th International Conference on Ground Control in Mining, S.S. Peng, C. Mark and A.W. Khair (eds), 7–9 August 2001, WV Univ., Morgantown, USA,
Mark, C. (2000) Design of Roof Bolt Systems, in New Technology for Coal Mine Roof Support, NIOSH Open Industry Briefing, C. Mark, D.R. Dolinar and R. Tuchman (eds), Department of Health and Human Services, National Institute for Occupational Safety and Health, IC 9453, 2000, pp. 111–132.
Mark, C. and Mucho, T.P. (1994) Longwall Mine Design for Control of Horizontal Stress, in Proceedings New Technology for Longwall Ground Control, U.S. Bureau of Mines Technology Transfer Seminar, Special Publication 01–94,1994, 12 April and 10 May 1994, Washington and Denver, USA, pp. 53–76.
Mine Safety & Health Administration (MSHA) (2012) US Department of Labor, Arlington, VA, USA, viewed 13 March 2013,
Molinda, G.M., Mark, C. and Dolinar, D.R. (2000) Assessing Coal Mine Roof Stability through Roof Fall Analysis, in New Technology for Coal Mine Roof Support NIOSH Open Industry Briefing, C. Mark, D.R. Dolinar, and R. Tuchman (eds), Department of Health and Human Services, National Institute for Occupational Safety and Health, IC 9453, 2000, pp. 53–72.
Molinda, G.M. and Mark, C. (1996) Rating the Strength of Coal Mine Roof Rocks, U.S. Department of the Interior, Bureau of Mines, Pittsburgh, IC 9444. 36 p.
Molinda, G.M. and Mark, C. (1994) Coal Mine Roof Rating (CMRR): A Practical Rock Mass Rating for Coal Mines, Pittsburgh, Pennsylvania, U.S. Department of the Interior, Bureau of Mines, IC 9387, 83 p.
Oyler, D.C., Mark, C., Gale, W.J. and Chen, J. (2004) Performance of Roof Support Under High Stress in a U.S. Coal Mine, SME preprint 04–135, Society for Mining, Metallurgy, and Exploration, Inc., Littleton, 7 p.
Pierce, M., Mas Ivars, D., Cundall, P. and Potyondy, D. (2007) A synthetic rock mass model for jointed rock, in Proceedings 1st Canada-US Rock Mechanics Symposium, E. Eberhardt, D. Stead and T. Morrison (eds), 27–31 May 2007, Vancouver, Canada, Taylor & Francis, London, pp. 341–349.
Spearing, A.J.S. and Gadde, M. (2011) Improving underground safety by understanding the interaction between primary rock bolts and the immediate roof strata, Final Report (Oct. 2011), NIOSH Contract No. 200–2009–32518 (2009), 283 p.
Tulu, I.B., Esterhuizen, G.S. and Heasley, K. (2012) Calibration of FLAC3D to Simulate the Shear Resistance of Fully Grouted Rock Bolts, in Proceedings 46th US Rock Mechanics/Geomechanics Symposium, A. Bobet (ed), 24–27 June 2012, Chicaco, USA, 11 p.
Zienkiewicz, O.C., Humpheson, C. and Lewis, R.W. (1975) Associated and Non-Associated Visco-Plasticity and Plasticity in Soil Mechanics, Geotechnique, Vol. 25, pp. 617–689.
Zipf, R.K. (2006) Numerical modeling procedures for practical coal mine design, in Proceedings 41st U.S. Rock Mechanics Symposium, D.P. Yale, S.C. Holtz, C. Breeds and U. Ozbay (eds), 17–21 June 2006, Golden, USA, American Rock Mechanics Association, Alexandria, 11 p.