Fault slip bursts induced by mining activities could inflict severe damage to mine openings. In this paper, dynamic modelling of mining-induced fault slip is demonstrated with the purpose of examining an effect of a variety of factors, such as mining depth and the angle of friction, on seismic response of the fault slip, using a numerical model with a fault parallel to a steeply dipping ore body that is mined out with sublevel stoping method. The results obtained from the analyses show that fault-slip could become significantly violent when mining depth increases or when the angle of friction decreases, while the shear stiffness and dilation angle of the fault do not exert a severe influence on the behaviour of the fault. It is also shown that significantly high shear rupture velocity could be induced by extracting the orebody parallel to the fault.

1 Introduction

Fault slip burst could pose a severe threat to nearby openings in underground hard rock mines, where existence of faults is not uncommon. Many attempts have been made in order to estimate a magnitude and location of the fault slip in underground mines, considering progress of mining activities. Hofmann & Scheepers (2011) simulated fault-slip areas by comparing results obtained from numerical analysis with data captured by microseismic monitoring system. Estimating cumulative seismic moment while simulating progress of mining sequences over a long period has been performed (Sjoberg et al. 2012). In terms of the locations of fault-slip, Alber et al. (2008) attempted to associate mining activities with the occurrence of seismic events in geological structures. Owing to the studies, better understanding of fault slip related seismic events has been achieved.

However, fault-slip burst is a dynamic phenomenon, which gives rise to seismic waves that propagate through rockmasses and could cause severe damage when hitting surfaces of mine openings where stresses are concentrated. According to Blake & Hedley (2003), fault-slip burst that took place in Wright-Hargreaves Mine in 1964 caused significant damage to mine openings from 2550 level to 3750 level, which resulted from seismic waves. Although static analysis is capable of simulating shear displacement increments and stress change induced by the fault slip, dynamic analysis is indispensable to simulate the seismic waves.

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