Numerical modelling to investigate the effects of blasting in confined rock Simulation of a field study

A field experiment was carried out to investigate the explosive/rock interaction in confined and highly stressed rock ahead of a development end (tunnel) at 2.7 km below surface. A total of four test blasts were carried out in the tunnel. The explosive type and amount, blasthole diameter and length, and stemming material type were varied with each blast. The results obtained from an extensive instrumentation and blast monitoring programme indicated that the stress field in the vicinity of the blasthole was changed both in magnitude and orientation. The induced fracturing by the blast was observed and mapped by advancing the tunnel in the direction of the blasthole. The computer program DIGS (Discontinuity Interaction and Growth Simulation) was used to simulate the propagation of multiple fractures from a blasthole due to the gas pressure generated by the explosive charge. The results obtained from numerical modelling studies showed close similarity with the field observations.