ABSTRACT
Rockbursts in the Upper Silesian Coal Basin (USCB) have represented a very dangerous phenomenon for a long time (e.g. Konicek et al. 2011). The rockburst problem relates primarily to the existence of competent rocks in rockmass and to the non-uniform stress fields induced by long-term excavation. The occurrence of a critical stress field leads to the brittle failure of coal and also of adjacent rocks. Such rockbursts are usually the result of long-term formation of unfavourable stress conditions in a specific geological structure (Holecko et al. 1999). The impact of destress blasting on the original high
stress concentration ahead of advanced longwall face is main goal of our stress research. There is a general consensus that destress blasting softens the rock and reduces its effective elastic deformation modulus. There are conflicting views over the importance of the destress blasting for reducing the stress and the stored strain energy from the rock (e.g. Sedlak 1997, Konicek et al. 2013). Destress rock blasting has been used in underground coal mining in the Czech part of the USCB since 1990 to prevent rockbursts and more than 2000 destress rock blastings occurred in this region between 1990 and 2010 to rockbursts control (Konicek et al. 2011). This paper presents the first results for in situ stress
and measured changes. The measurement was carried out in a selected longwall panel in the Czech part of the USCB.
