Authors: Johnson, JD; Fergusson, D; Guy, G

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Johnson, JD, Fergusson, D & Guy, G 2007, 'Risk Based Slope Design for Opencast Coal Mines at Rotowaro, Huntly, New Zealand', in Y Potvin (ed.), Slope Stability 2007: Proceedings of the 2007 International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 157-170,

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This paper presents an overview of the history of open pit slope design within the Rotowaro Coalfield, Huntly New Zealand and discusses how these approaches have been successfully adopted in recent years to manage slope instability risk. Discussion is presented on the application of conventional 2-dimensional slope analysis at Rotowaro and the background to the development of quantitative risk-based slope design methods. The application of a ‘risk volume’ as design criteria is outlined. The limitations of these approaches for larger slopes are noted and discussed. Comparisons of 2-D and 3-D analytical approaches using limit equilibrium methods are presented. A discussion on the validity of assessed weak rock mass strengths at high normal stress is also provided, together with how these effects are being investigated using numerical models. A comparison of slope stability findings from limit equilibrium and finite difference modelling are discussed along with the implications for slope design and risk management.

Dewerse, R.R. (2005) Load deformation modelling of a soft rock highwall, thesis from degree of master of engineering
University of Auckland NZ.
Duncan, K.J. (2002) The shear strength of rock masses. Phd thesis, University of New South Wales, Sydney Australia.
Edbrooke, S.W., Sykes, R. and Pocknall, D.T. (1994) Geology of the Waikato Coal Measures Waikato Coal Region
New Zealand. Institute of Geological and Nuclear Sciences Monograph 6.
Fergusson, D., Paris, M., Anderson, C.K., McMorran, T. and Johnson, J.D. (2001) Opencast Highwall Slope Design
Rotowaro Coalfield. Proceedings Engineering and Development in Hazardous Terrain New Zealand
Geotechnical Society Symposium, pp. 35-51.
Hegan, B.D. and Read, S.A.L. (1988) A mechanism for slope failure observed in open pits, Northern Waikato Region
New Zealand. Fifth Aus-NZ Conference on Geomechanics.
Itasca (2001) Itasca Software Products - FLAC, FLAC3-D, UDEC, Itasca Consulting Group Inc., Minneapolis.
Kear, D. and Waterhouse, B.C. (1978) Waikato Coal Fields: Rotowaro Coalfield 1:15840. New Zealand Geological
Survey Miscellaneous Series Map 9 (Geology) and 10A (Mining) maps (3) and notes.
Read, S.A.L., Perrin, N.D. and Richards, L. (2006) Evaluation of the intact properties of weak rocks for use in the Hoek
Brown failure criterion, ARMA/USRMS 05-694.
Richards, L. and Read, S.A.L. (2006) A review of empirical methods for assessing rock mass deformability, ARMA
/USRMS 06-1169.
Stead, D., Eberhardt, E. and Coggan, J.S. (2006) Developments in the characterisation of complex rock slope
deformations and failure using numerical modelling techniques. Engineering Geology 83, pp. 217 -235.
Yang, J. and Hu, D.X. (2006) Deformation and Safety Analyses on a High Rock Slope at the Left Bank of Lijiaxia Arch
Dam. Proceedings of Sessions of GeoShanghai, June 6–8, 2006, Shanghai, China.
Risk Based Slope Design for Opencast Coal Mines at Rotowaro, Huntly, New Zealand J.D. Johnson, et al.
170 Slope Stability 2007, Perth, Australia

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