Rockburst hazard evaluation and prevention methods in Polish copper mines

Longstanding mining of copper deposit in the Legnica-Glogow Mining Basin (LGOM area) enabled to gain broad experience concerning the impact of geological and mining conditions on seismic and rockburst hazard. Basing on gathered data, the methods of rockburst prevention for deep copper mines were developed. Methods of rockburst hazard evaluation as well as rockburst control methods constitute a set of rockburst prevention. The prevention methods due to their nature and location within the production process can be the passive and the active ones. Active methods of rockburst prevention consist in liquidation of stresses in the areas of their concentration through controlled generation of rock-mass tremors and rockburst by blasting works (group winning blasting, release blasting in rock-mass and in pillars able to accumulate the stress as well as in the roof and floor). Whereas the group blasting works as a basic method are very effective in the copper mines conditions. Provocation of dynamic events makes possible the control of time of their occurrence. In Polish copper mines all blasting works are made during the absence of miners in the mining fields. Daily distribution of both the number of recorded strong seismic events and the volume of energy released confirm the advisability of using this kind of rockburst hazard prevention. The rockburst hazard prevention methods developed during the 40 years of copper deposit extraction are economically reasonable and offer the sufficient effectiveness under the high rockburst hazard conditions.