Distress Blasting on a Mining Face in High Horizontal Stress Environment

ABSTRACT: This paper describes a finite element modelling technique for the simulation of destress blasting in hard rock mining operations at depth. The technique employs two newly introduced parameters, a, a rock fragmentation factor, and ß, a stress dissipation factor, inside the modeled, des tressed zone. Destress blasting is simulated by modifying the deformation properties of the rockmass and the post-blast state of stress in the destressed zone using the above-mentioned parameters a and ß. The technique, based on incremental analysis, permits the simulation of actual mining, i.e. mining and destressing. This paper examines the effectiveness of destress blasting in underground drift development at depth. In particular, the following parameters are studied; (1) Magnitude of horizontal stress (or depth below surface), (2) Horizontal-to-vertical stress ratio, and (3) Orientation of drift axis with respect to the major horizontal in situ stress. The results of a detailed parametric study are reported.