Authors: Haile, A; Ross, D; Maldonado, A; Neyaz, M; Rajbhandari, C

Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2025_23

Cite As:
Haile, A, Ross, D, Maldonado, A, Neyaz, M & Rajbhandari, C 2020, 'BHP Western Australia Iron Ore geotechnical open cut slope design system: a simple pragmatic process for slope risk decisions', in PM Dight (ed.), Proceedings of the 2020 International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, Australian Centre for Geomechanics, Perth, pp. 415-426, https://doi.org/10.36487/ACG_repo/2025_23

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
A transparent, pragmatic geotechnical design system is outlined that presents a selection of risk options with associated risk/reward for decision makers. Risk options termed ‘robust’, ‘balanced’ and ‘aggressive’ have been defined appropriate to ‘critical infrastructure’, ‘typical industry’ and ‘low risk’ mining environments (where the safety risk and the consequences of failure on the budgeted mine plan are acceptably low), respectively. The geotechnical model includes ‘most realistic’ and ‘reasonable lower case’ conditions. A ‘realistic’ design principle requires reporting a Factor of Safety on the realistic case, rather than to reduce design inputs due to uncertainty. Uncertainty is transparently covered by the ‘lower case’ in sensitivity analyses. Indicative probabilities of failure are estimated and a simple empirical tool estimates the consequence of failure in terms of the area of mining floor impacted. These together with indicative value or tonnage estimates are presented to the decision maker (risk owner), with a selection recommendation. Post decisions, designs including any residual hazards are passed to the operational engineers to design risk-based slope monitoring, to ensure operational safety, and reconciliation programs, as required. Adoption of the realistic principle has facilitated risk owners taking decisions based on a more transparent presentation of risk since 2014 and made a material contribution to a step change slope angle increase in the mines of BHP Western Australian Iron Ore.

Keywords: design, uncertainty, failure, risk Confidential. © BHP 2020. No information in, or part of, this document may be reproduced or disclosed without the express written permission of BHP.

References:
Call, RD 1992, ‘Slope Stability’, in HL Hartman (ed.), SME Mining Engineering Handbook, Society for Mining, Metallurgy & Exploration, Englewood, pp. 881–896.
Finlay, PJ, Mostyn, GR & Fell, R 1999, ‘Landslide risk assessment: prediction of travel distance’, Canadian Geotechnical Journal, vol. 18, no. 3, pp. 556–562.
Mercer, KG 2012, ‘The history and development of the anisotropic linear model: part 1’, Australian Centre for Geomechanics July Newsletter, Australian Centre for Geomechanics, Perth, vol. 38, pp. 13–16.
Maldonado, A & Haile A, 2015, ‘Application of ANOVA and Tuckey-Cramer, statistical analysis to determine similarity of rock mass strength properties across Banded Iron Formations of the Pilbara region in Western Australia’, Proceedings of the International Symposium on Slope Stability in Open Pit Mining and Civil Engineering, South African Institute of Mining and Metallurgy, Johannesburg, pp. 1–19.
Maldonado, A 2017, The basic friction angle and nominal roughness for Pilbara defects, BHP internal report.
Ryan, TM & Pryor, PR 2000, ‘Designing catch benches and interramp slopes’, in WA Hustrulid, MK Carter & DJA Van Zyl (eds), Slope Stability in Surface Mining, SME Colorado, pp. 27–38.
Wesseloo, J & Read, J 2009, ‘Acceptance Criteria’, in J Read & P Stacey (eds), Guidelines for Open Pit Slope Design, CSIRO, Melbourne.
Whittall, JR 2015, Runout Exceedance Prediction for Open Pit Slope Failures, MSc Thesis, University of British Columbia, Vancouver.




© Copyright 2020, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to repository-acg@uwa.edu.au