The use of a multipole expansion technique to analyse large scale fracture processes and seismic recurrence effects in deep level mines

Abstract

An efficient solution technique for the analysis of multiple interacting displacement discontinuities is described together with the implementation of a viscoplastic relaxation model for the simulation of observed time dependent seismic activity in deep level gold mines. The method is illustrated in relation to the mining of a parallel sided panel with attendant mobilization of fractures in the surrounding rock. A comparison is made between the case where mining is advanced continually by a constant increment every day and the case where mining is interrupted every seventh day corresponding to a weekend break. Some possible methods of analysing the seismic recurrence cycles that are induced by the mining are presented. For the simple cases studied it is found that there is no apparent correlation between successive seismic energy release peaks. It appears that slightly more seismic energy is released in the continuous mining cycle than in the case where the mining is interrupted every seventh day.