Materiały konferencyjne SEP 1992

Szkoła Eksploatacji Podziemnej * 92 429 investigation would be applied in 1992 in other mines. Preyention of rock bursts comprises active and passive measu- res taken to prevent the release of a rock burst. Actłve measu- res consist in: - liąuidation of sources and causes of critical accumulation of energy in rock mass, - modlfication of properties of structural unlts of rock mass ahead of the mining face, - modification of the process of failure (fracturing) of struc- tural units of rock mass during the mining. Passive measures of prevention consist in provoking a rock burst In the absence of men at the face. The aim is to protect men and eąuipment In cases when there were bursts even though active preventive measures had taken with anticipation. The pre- sent knowledge on rock bursts and technical means availabie to prevent them are still an sufficient. Therefore, passive measures of prevention are included, as a rule, in the projects of pre- yent ion worked out for the coal faces and roadways. In OKD the following active measures are used most freąuen tly: - strategie measures, - drilling of boreholes to relieve stresses in rock mass^ - infusion of water in the seams, - distressing blasting works in coal, ~ water infusion or blasting works in the roof of the seam being worked. The experience of OKD has shown that strategie measures (i.e. adeąuate layout of the face from the point of view of the danger of rock burst) are most important. The majority of rock bursts were induced by previous mining which did not correspond to the principles of strategy. On the other hand, the mining practice has demonstrated that the observat ion of strategie principles is not always possible, e. g. for the fol lowing rea- sons: - The layout the mine was made for levels where there was not yet the danger of rock burst. In deeper levels, the anti-rock burst regime had to be introduced additionally. - Natural conditions of the mining are so complicated that stra-