A semi-quantitative approach to pit slope design acceptance

Authors: Sharp, M; Yost, R Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2535_01

Cite As:
Sharp, M & Yost, R 2025, 'A semi-quantitative approach to pit slope design acceptance', in JJ Potter & J Wesseloo (eds), SSIM 2025: Fourth International Slope Stability in Mining Conference, Australian Centre for Geomechanics, Perth, https://doi.org/10.36487/ACG_repo/2535_01



Abstract:
Current geotechnical practice for pit slope design typically involves a binary approach to design acceptance by defining a minimum Factor of Safety based on consequence of failure – the slope equals or exceeds the acceptance criteria, or it doesn’t. While this approach could be appropriate for simplified geometries and lower pit slope heights, it may not capture the innate uncertainty and complexity that exists with increasingly sophisticated pit slope stability modelling analysis and large, complex, pit slopes. The acceptance of a design should not solely be based on the result of a stability model, but rather, the stability model should be used as one indication. This paper presents a semi-quantitative approach for inter-ramp to global-scale pit slope design, by incorporating a range of slope stability indicators – such as stability and deformation modelling results, empirical performance, failure predictability, and level of uncertainty – and combining these indicators into one stability rating. Design acceptance criteria are defined by a stability target based on consequence of failure, and the ability to predict and manage slope instability. This allows for a strategic and comprehensive risk-based approach to pit slope design that aims to explicitly identify areas of uncertainty and risk.

Keywords: design acceptance, stability indicators, performance-based design, risk management

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