Seismic response of large-scale to medium-scale geological structures in deep mines

Authors: Falmagne, V; Doucet, C; Yergeau, D; St-Onge, N; Durham, C; Jacobs, R; Pyy, A; Heller, A Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2465_04

Cite As:
Falmagne, V, Doucet, C, Yergeau, D, St-Onge, N, Durham, C, Jacobs, R, Pyy, A & Heller, A 2024, 'Seismic response of large-scale to medium-scale geological structures in deep mines', 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. 153-170, https://doi.org/10.36487/ACG_repo/2465_04



Abstract:
Successful mining projects rely on three interconnected pillars: maintaining a safe working environment, achieving uninterrupted production at the required mining rate and ore grade, and managing costs effectively. A strong seismic response either during mine development or stope extraction constitutes a potential safety hazard and it can eventually affect the delivery of the mine plan. The anticipated rock mass behaviour around mine excavations depends on the effect of the in situ stress field on local rock mass conditions. Both are directly related to the geological and tectonic history of the deposit and regional environment. The geometry, strength and stiffness of large-scale structural features such as brittle faults, ductile shear zones and dykes have a direct and significant impact on the surrounding rock masses and local stress field. The Goldex and LaRonde mines in Canada, and the Kittilä mine in Finland, are deep underground seismically active mines in different geological settings. The seismic responses of medium to large-scale geological structures and dykes encountered at Goldex and select examples from LaRonde and Kittilä mines illustrate some of the lessons and ongoing work to assist in managing the seismic risk at these operations. The seismic response of large to medium-scale structures is challenging to anticipate and manage until actual mining has taken place and monitoring data is available. For instance, the seismic response associated with graphitic shears and jointing in the footwall at Rimpi, the milder-than-expected response of the diabase dykes and the stronger than expected response of the mylonitic ductile shears and brittle faults at Goldex were unforeseen. Even in a mature mine such as LaRonde, the understanding of the behaviour of the 700 Fault has taken some time to develop. The examples provided in this paper aim to demonstrate the benefits of integrating structural geology and improving the characterisation and modelling of the large to medium-scale structures from the earliest stages of a project. In mature mining camps, leveraging the geological and deformation history from regional geology and tectonic setting can help to anticipate potential alteration patterns and large-scale structural orientations and dykes. These structures should be included in early analyses and numerical modelling to guide the placement of mine infrastructure, strategic mine layout and mining sequence decisions.

Keywords: geological structures, litho-structural model, seismic response, tectonic setting

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