Underground longwall mining of coal seams in the Upper Silesian Coal Basin is currently being carried out under increasingly difficult geological and mining conditions. Mining depth, dislocations and mining remnants are the main factors responsible for the most significant rockburst hazard, which can be minimized via the use of active and passive rockburst prevention. Active rockburst prevention in longwalls is usually based on blasting, in order to either destress local stress concentrations in the rock mass or to fracture the thick layers of strong roof rocks to prevent or minimize the impact of high energy tremors on excavations. The accurate estimation of active rockburst prevention effectiveness is particularly important when mining under disadvantageous geological and mining conditions, which are associated with high levels of this hazard. The efficiency of blasting applied for this purpose is typically evaluated from the seismic effect, which is calculated based on seismic monitoring data and the weight of the charged explosive. This method, as used previously in the Czech Republic, was adopted in the present study to analyze conditions occurring in a Polish hard coal mine in the Upper Silesian Coal Basin. Parameters of long hole destress blastings in roof rocks (torpedo blastings) from the face of the assigned longwall in coal seam no. 507 were correct a success according to the seismic effect method and corresponded to observations made in situ. The analytical method presented enables the rapid estimation of destress blasting effectiveness and could also be useful when determining appropriate active rockburst prevention.
W kopalni „Bielszowice” zaprojektowano eksploatację pokładu 405/2wg (o grubości do 8,6 m) ścianą 839a. Pokład 405/2wg, zaliczony do III-go stopnia zagrożenia tąpaniami, zalega w tym rejonie na głębokości do około 1020 m. Podczas wcześniejszej eksploatacji tego pokładu w tej części złoża występowały zjawiska dynamiczne. Skuteczna i bezpieczna eksploatacja pokładu 405/2wg ścianą 839a wymagała zaprojektowania odpowiedniej profilaktyki tąpaniowej. Doświadczenia umożliwią kontynuację eksploatacji tego pokładu kolejnymi ścianami aż do głębokości 1200 m (ściana 840).
EN
In „Bielszowice" mine exploitation of seam 405/2wg (thickness up to 8.6 m) by longwall 839a has been designed. Seam 405/2wg, classified to the third category of rock burst hazard, and is bedded in this area at a depth of about 1 020 m. During previous exploitation of the seam in this part of the deposit dynamic phenomena were occurring. Effective and safe extraction of seam 405/2wg by longwall 839a required designing of appropriate rock burst prevention measures. The experience will enable the continuation of exploitation of this seam by successive longwalls up to the depth of 1200 m (longwall 840).
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