A risk-based methodology to improve the definition of geotechnical sectors in slope design

In the planning of open pit mines, it is often difficult to determine the shapes and sizes of slope design sectors prior to their analysis, particularly in structurally complex geological environments. This problem is exacerbated in sectors encompassing significant strike changes of lithological uni...

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Bibliographic Details
Published in:Journal of the South African Institute of Mining and Metallurgy 2019-12, Vol.119 (12), p.1027
Main Authors: Bester, M, Stacey, TR, Basson, I, Koegelenberg, C, Creus, P, Lorig, L, Cabrera, A
Format: Article
Language:English
Subjects:
Design parameters
Geology
Geotechnical engineering
Geotechnical models
Lithology
Mathematical models
Open pit mining
Parameter uncertainty
Risk assessment
Rock masses
Stability analysis
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Summary:In the planning of open pit mines, it is often difficult to determine the shapes and sizes of slope design sectors prior to their analysis, particularly in structurally complex geological environments. This problem is exacerbated in sectors encompassing significant strike changes of lithological units or contacts. This variability in strike is often poorly addressed/represented by applying median values or averages for key parameters, thereby increasing uncertainty and risk. The design process may be improved by the early identification of specific lithological units – of any shape or size – that show unfavourable interaction of geological features with slope geometries on future pushbacks or on final designs, utilizing inputs from apparent dip analysis and synthetic rock mass modelling. Focused data acquisition and more rigorous stability analysis in areas of concern will result in more robust and practical sector-specific design parameters, typically applied in block model format as inputs for mine design. A case study at Sishen mine, in the Northern Cape Province of South Africa, demonstrates that an ongoing, risk-based approach leads to a higher-confidence dynamic geotechnical model, thereby allowing for an integrated mine design process with the ultimate goal of achieving early risk mitigation and delivering optimized designs that unlock significant value without compromising the geotechnical risk profile of the mine.
ISSN:0038-223X
2411-9717
DOI:10.17159/2411-9717/685/2019