Preconditioning to reduce incidence of face bursts of highly stressed faces.

Abstract

Preconditioning or distressing as it was initially called, was first introduced as means of ameliorating rockburst conditions in deep mines by the management of the East Rand Proprietory Mines (ERPM) in the early 1950’s with the cooperation and guidance of CSIR. The principle on which distressing was based at the time that “The occurrence of rock bursts might be reduced or their violence decreased by increasing the depth of the fracture zone at the face of the working stope”. The argument for this was based on the concept that if the holes drilled at right angles into the face were blasted they would advanced the depth of fracturing and in so doing transfer the high stress zone further away from the face into the solid.