TECHNOLOGY OF COUPLED PERMEABILITY ENHANCEMENT OF HYDRAULIC PUNCHING AND DEEP-HOLE PRE-SPLITTING BLASTING IN A "THREE-SOFT" COAL SEAM
Abstract
Aiming at the problems of poor gas permeability, serious difficulty in gas extraction and low pre-extraction efficiency of the "three-soft" coal seam in the Zhengzhou mining area, a co-penetration technology of hydraulic punching and deep-hole pre-splitting blasting is put forward, and the mechanism of the co-penetration of hydraulic punching and deep-hole pre-cracking blasting is analyzed. Based on the theory of explosive dynamics and fracture mechanics, a numerical simulation method was adopted to study the stress distribution and propagation law of blast cracks in coal for different spaces between a blast hole and control extraction hole, and the reasonable space between the two blast holes is determined to be 4 m. Through a field test of the Zhengzhou Coal Group GC Coal Mine, No. 188 Zhongyuan West Road, Zhongyuan District, Zhengzhou City, it is shown that the penetration effect after pre-cracking blasting is significant, the average and maximum purity of the gas extraction in the adjacent four groups after blasting reach 0.065 m3/min and 0.11 m3/min, respectively, which is 2.5 and 5.5 times more than before blasting, and the permeability of the coal body near the blast hole reaches 2.47 m2/(Mpa2·d), which is 466 times higher than that of the original coal body and 5.5 times higher than after the hydraulic-punching measures.
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