Mapping cave front growth utilising the collective behaviour of seismicity and velocity fields

Authors: Viegas, G; Bosman, K; Angus, D; de Beer, W; Urbancic, T

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DOI https://doi.org/10.36487/ACG_rep/1815_45_Urbancic

Cite As:
Viegas, G, Bosman, K, Angus, D, de Beer, W & Urbancic, T 2018, 'Mapping cave front growth utilising the collective behaviour of seismicity and velocity fields', in Y Potvin & J Jakubec (eds), Caving 2018: Proceedings of the Fourth International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 577-588, https://doi.org/10.36487/ACG_rep/1815_45_Urbancic

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Abstract:
In many block caving operations, the expansion and growth of the cave involves an examination of the distribution of seismicity both spatially and temporally around the cave itself. These approaches utilise event density as a proxy to define the volume of fractured rock mass and provide a ‘sense’ of cave front migration. However, seismic records contain a wealth of information not only about the location of fractures, but the volume encompassing the fractures (source volume) and the relative stress state of the rock mass surrounding the caving operation with distance from the cave itself. This leads to considering that observed seismicity is part of a collective response of the rock mass due to mining. We suggest that event occurrence is related to the dynamic stress conditions associated with the caving operation. In this manner, we can consider the collective behaviour of seismicity, specifically the energy and stress release states, and map, along with velocity variations, the degree of fracturing relative to the cave boundary. Here, we provide examples of how these approaches enhance our understanding of block caving and the growth of the caving front in space and time. Specifically, we identify how stress can be tracked ahead of the observed event distribution clouds and the relative degree of fracturing that occurs in the highly stressed zone.

Keywords: cave growth, fractures, collective response, stress release, stress tracking

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