The critical earthquake concept applied to block caving — evidence for cooperative behaviour during failure

Authors: White, H; van As, A; White, D; O'Keefe, B Paper is not available for download Contact Us

DOI https://doi.org/10.36487/ACG_rep/1002_2_White

Cite As:
White, H, van As, A, White, D & O'Keefe, B 2010, 'The critical earthquake concept applied to block caving — evidence for cooperative behaviour during failure', in Y Potvin (ed.), Caving 2010: Proceedings of the Second International Symposium on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 83-91, https://doi.org/10.36487/ACG_rep/1002_2_White



Abstract:
Block caving is a mining method in which an orebody effectively collapses under its own weight once a sufficient area has been undercut. The ability of the rock mass to cave under its own weight is governed in large part by failure along structures within the rock mass, whether they be distinct, major faults or shears or simply microdefects in the rock fabric. Most of the associated shear failure along these structures is detected through mine microseismic monitoring systems and provides engineers with a wealth of information regarding the rock mass’ response to caving. During cave progression, the seismic response yields valuable information regarding the caving process. In particular, we have observed faster-than-exponential increases in seismic source parameters during cave propagation at Northparkes’ E26 Lift 2, suggesting that the cave is showing self-organised critical behaviour (Helmstetter and Sornette, 2002). This type of behaviour is particularly symptomatic of the caveability of geotechnical domains within the block and thus may help identify: if parts of the orebody are not in a state of criticality prior to the initiation of the cave, then it is possible that these may remain unaffected by the caving process the time dependence of the source parameters could be used to predict cave break-through changes in the deviatoric stress that are sufficient to initiate and sustain seismic activity associated with caving, thereby assisting in the design strategy for cave induction or rock mass preconditioning that will promote sustained seismicity, i.e. continuous caving.

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