Beer, AJ & Morrongiello, MR 2007, 'Wall Optimisation - A Case Study From the Fimiston Open Pit, Kalgoorlie Consolidated Gold Mines', 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. 403-415, https://doi.org/10.36487/ACG_repo/708_26
During 2006, Kalgoorlie Consolidated Gold Mines’ (KCGM) Geotechnical Section led a wall optimisation
project for the Fimiston Open Pit. The 2006 stage of the project was aimed at bringing this increase into the
‘probable reserve’ category. The 2006 project has also identified the further studies which will be necessary
to move this reserve increase up to the ‘proven’ category.
The project re-assessed assumptions made in a 1989 report, based on near-surface exposures. Observed pit
wall structures and behaviour led to the decision to re-evaluate the optimum wall angle. For the first stage of
the project, mainly existing data has been used, and primarily rock mass property data collected since 1990,
but also structural data from the mapping of the old underground workings. The results from a major
groundwater modelling project provided information as to the location of the phreatic surface which was
used as an input to the modelling.
For the 2006 stage of the project, probability of failure was calculated using Rosenblueth’s (1975) Point
Estimation Method to pick values for rock mass parameters. These values were then used to generate shear-
normal functions for the rock mass which provided input parameters to the SLIDE™ package (Rocscience,
2005), the probability of failure being obtained from the mean and standard deviation of the factors of safety
Beer, A.J. (2006a) Slope Stability Modelling of East Wall Re-design October 2006. Unpublished Internal KCGM
Beer, A.J. (2006b) Slope Stability Modelling of East Wall Re-design October 2006. Addendum. Unpublished Internal
Beer, A.J. (2006c) Slope Stability Modelling of East Wall Re-design October 2006. Addendum 2. Unpublished Internal
Haines, A. (1993) Rock Slope classification for the optimal design of monitoring networks. In Proceedings of the
Australian Conference on Geotechnical Instrumentation and Monitoring in Open Pit and Underground Mining,
T. Szwedzicki (ed.), Kalgoorlie, Western Australia, 21-23 June 1993, Balkema, Rotterdam, pp. 201-209.
Hoek, E. and Brown, E.T. (1997) Practical estimates of rock mass strength. International Journal of Rock Mechanics &
Geomechanics Abstracts. 34(8), pp. 1165-1186.
Morrongiello, M. (2003) 2003 Fimiston Groundwater Report. Unpublished KCGM Geology internal report.
Pickens, G. (2006). Fimiston Structural Model 2006. Unpublished KCGM Report 2006.
Rocscience (2005) SLIDE Version 5.0, Rocscience Inc., Ontario, Canada,
Rosenblueth, E. (1975) Point Estimates for Probability Moments. Proceedings of the National Academy of Science of
the USA, 72 (10).
Sarunic, W. (2006) Geotechnical Review for the Trafalgar Cutback. Unpublished Memo Report from Snowden Mining
Consultants dated 21st December 2006.
Stacey, P.F. (2004) Pit Slope Stability Review – November 2004. Unpublished Letter report from Stacey Mining
Geotechnical to KCGM.
Wines, D.R. (2001a) Aspects of Rock Slope Engineering at the Fimiston Open Pits. Unpublished MSc Thesis, Curtin
University of Technology.
Wines, D.R. (2001b) Geotechnical Status Report Oroya Cutback. Unpublished KCGM Geotechnical internal report.
Zhan, J. (2006) Kalgoorlie Consolidated Gold Mines Fimiston Pit Lake Water Balance Model. Unpublished Barrick
Rock Slope Stability
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