Abstract
In many parts of the world, rockbursts have become a major problem of mining at depth. As orebodies are being mined deeper, rockburst phenomena have become familiar to deep hard rock mines. Rockbursts are generally characterised by sudden release of energy in a volume of highly stressed rock, which can cause local violent failure of the rock mass around the opening. One method of controlling these failures is to precondition the rock mass by detonating fully confined explosive charges at the appropriate locations. This method known as destress blasting, was first tried in the deep South African gold mines (Roux et al., 1957), and was widely used later in Canada, United States, France, Poland and Japan.
The in situ conditions leading to the occurrence of rockbursts and the possibilities of using destress blasting to control them are presented. Information such as: geology, rock properties, in situ stresses and mine excavation rate and configuration as well as blasting parameters such as: blasthole layout, hole length, explosives loading and ignition schemes have been collected, and currently are being compiled in a database. The review shows that some mine operations have successfully used destress blasting to their benefit, sometimes requiring other changes in their operational procedures. Applications, techniques and results garnered from this world-wide survey of destress blasting trials and programs, some successful and some not, are analysed and discussed. Logical, engineering explanations for the results obtained are proposed.