Numerical model calibration of fault properties using seismic moment for a deep underground mine

Authors: Maldonado, C; Katsaga, T; Li, H Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2465_47

Cite As:
Maldonado, C, Katsaga, T & Li, H 2024, 'Numerical model calibration of fault properties using seismic moment for a deep underground mine ', in P Andrieux & D Cumming-Potvin (eds), Deep Mining 2024: Proceedings of the 10th International Conference on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 757-766, https://doi.org/10.36487/ACG_repo/2465_47



Abstract:
Microseismicity often provides crucial insights into the behaviour of rock masses in deep mining environments, especially concerning damage and the mechanisms affected by stress field changes. By integrating numerical simulations of synthetic microseismicity with field data analysis, a comprehensive understanding of damage initiation, progression, and the interactions among discontinuities can be attained. This holistic approach not only advances our comprehension of rock mass behaviour in deep mining operations but also enables more precise predictions and proactive management strategies to mitigate risks.  This study delves into the methodology employed for calibrating numerical models, focusing on the geological structures within a deep mine in Canada. The occurrence of significant seismic events in this deep mine is directly linked to fault slip. With mining operations delving deeper, understanding the stress-induced effects of mining and fault movements becomes paramount for ensuring safe ore extraction.  Merely incorporating lithological considerations into the numerical model proved to be insufficient to replicate the full behaviour of the rock mass response to seismic activity. Hence, fault structures were integrated into the model. However, due to the volumetric nature of faults with a thickness exceeding 1.5 m, explicit integration was deemed inadequate for accurately representing their behaviour. To address this challenge, a methodology termed the ‘weak zone’ approach was developed. With this approach, faults are characterised as relatively weaker materials compared to the host rock, and the cumulative plastic shear strain is utilised for calculating seismic moment.  Historically recorded seismicity served as a crucial calibration tool for determining the mechanical properties of faults within the model. These properties were then appropriately scaled to ensure that the modelled results provided a reasonable estimation of fault behaviours in relation to seismic moment. This comprehensive approach not only enhances our understanding of fault dynamics in deep mining environments but also aids in optimising safety measures for ore extraction. 

Keywords: fault behaviour, fault slip, seismicity, seismic moment, numerical model calibration

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