Approaches for Estimating Slope Breakback and Stability Longevity for Closure of Large Open Pits

DOI

10.2991/978-94-6463-258-3_49How to use a DOI?

Keywords

Open Pits; Slope Stability; Crest Breakback; Closure; Longevity

Abstract

Currently, few guidelines exist for how a practitioner should tackle the quantitative assessment of long-term slope performance for open pit mine closure design. Material degradation, resulting from cumulative incremental time-dependent deterioration and propagation of episodic damaging events (e.g., precipitation and seismicity) is of paramount importance in the closure context, as rockmass competence degradation largely controls long-term slope performance. Deterioration rates are governed not just by intrinsic (material specific) and extrinsic (environmental) factors, but also can be significantly affected by previous mining influences (principally blast damage, slope oversteepening, stress relief, etc.). Suggestions for various empirical, analytical and numerical modelling approaches for assessing impact of degradation on closure design risk are outlined and three key geotechnical closure design challenges for supporting design recommendations commensurate with planned post mining land use (PMLU) risk are discussed. These include:i) defining appropriate safe pit crest standoff distances, ii) assessing likely extent of long-term pit crest creep-strain tolerance zones, and iii) quantifying long-term overall slope stability. A risk-based approach is proposed, comprising initial susceptibility screening for time-dependent degradation, followed by increasing analysis rigour (commensurate with risk), starting with empirical assessments, moving then to first principle deterministic limit equilibrium calculations and finally escalating to numerical assessments involving sequentially calibrated time-stepped degradation models.

Copyright

© 2023 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Trevor G. Carter
AU  - Loren J. Lorig
AU  - Erik Eberhardt
AU  - Phil J. H. Graaf
PY  - 2023
DA  - 2023/11/08
TI  - Approaches for Estimating Slope Breakback and Stability Longevity for Closure of Large Open Pits
BT  - Proceedings of the Rocscience International Conference  (RIC 2023)
PB  - Atlantis Press
SP  - 505
EP  - 521
SN  - 2589-4943
UR  - https://doi.org/10.2991/978-94-6463-258-3_49
DO  - 10.2991/978-94-6463-258-3_49
ID  - Carter2023
ER  -