Stress changes and seismicity monitoring of hard coal longwall mining in high rockburst risk areas

Rockburst represents a very dangerous phenomenon in deep underground mining as well as in underground constructions in unfavourable conditions (great depth, high horizontal stress, proximity of important tectonic structures, etc.). The rockburst problem relates to the natural and mining conditions of the rock mass. It is very difficult to decide which of the factors prevails, but we generally assume that it is the occurrence of competent rock layers in the rock mass. The destress blasting method is a very important rockburst control technique aims to competent rocks. The case study describes the control of rockburst risk by destress blasting in an example of a longwall of the Upper Silesian Coal Basin. Monitoring of stress changes and induced seismicity was implemented in the selected longwall here and a description of these techniques is given. The paper describes the natural, geomechanical, and mining conditions of the investigated locality in detail. Stress changes ahead of the advancing longwall face as well as registered induced seismicity depending on the longwall advance are analysed, including the application of the destress blasting technique. Stress release efficiency, as one goal of the destress blasting technique, is analysed according to the registered seismicity using the authors' own methodology: seismic effect calculation.