A Survey of Blasting Efficiency

摘要

Many longwalls in the Ostrava-Karvina Coal Basin are mined under conditions of rockburst hazard. Therefore, as a part of the rockbursts preventative measures, large scale torpedo blasting operations carried out in the overlying strata have been applied. The main objective of these operations is to influence the stress-strain state of the rockmass on the basis of breaking up the roof rocks. The effectiveness of these preventative measures depends on the efficiency of individual explosions. The investigation into effectiveness of large scale torpedo blasting operations was performed using data gathered during mining operations of longwall No. 16419 in the Dukla mine. Efficiency has been calculated according to the empirical formula η - E_s[J]/(2.6 × Q[kg]) and the explosions were considered as effective when η ≥ 3 and as ineffective when η < 3.