Materiały konferencyjne SEP 1992

Szkoła Eksploatacji Podziemnej * 92 431 into the area around it whłch has a favourable effect on strength and deformation characteristics of the coal. This method has the advantage of ensuring also prevention against dust. There are a few problems which have not yet been solved satisfactori ly in this method. 11 is part icularly a rei iable checking of the effectivity of the infusion. A combłnation of the above mentioned there methods is made with the aim of increasing their efficiency. Water is infused through distressing boreholes or large charges of explosives are fired in them (there was a case of 1000 kg of explosives fired in a distressing borehole). The presence of thick layers of competent rocks of high strength in the roof of the seam being mined represents a great danger that a rock burst wi 11 be released. The aim of the prevention is to modify the properties and to reduce the homoge- neity of the roof. It can be achieved at last partially by water infusion or blasting in the roof. Deep boreholes for such measures have the diauneter of 42 to 75 mm for water infusion and 75 to 93 mm for blasting. The consumption of explosives is up to 3000 kg per round. Such blasting works must be made according to a special plan in which methane emissions and sełsmic effects on mine workings are considered. In OKD the production of coal from seams liable to rock bursts is sti 11 high, because the condit ions for mining~both geological and technical are still worse with advance to greater depth. The attached tables demonstrate the development of the parameters of rock bursts danger and prevention in OKD in the per i od 1981 -1990. We can say, that so much measures are be i ng taken to prevent the rock bursts occurrence and the complex solu- ton of rock bursts control is so expensive. To prove the effi- ciency of the whole system is very difficult» but it is impo- sible to Imaglne the possible conseąuences of coal mining in OKD without applying such system in conditions where the danger of rock burst is highly relevant.