Deep-hole pre-splitting blasting technology is recently applied to gas drainage through strata for increasing drainage rate in coal mine. At the background of the underground engineering practice, this study is to combine the 3-D numerical simulation with field test of drainage. Relations between dynamic stress distribution of each borehole and drainage effect after explosion are discussed. Layouts of control holes and blasting holes are analyzed according to the characteristics of gas drainage through strata. Mathematical models of deep-hole presplitting blasting through strata are established. As a blasting hole is oriented crossing a seam with an angle, dynamic stress distribution of different coal seam sections are extremely uneven; charge length of blast holes is an important factor affecting their radial extent of damage, while destruction radius increases 33% when the charge length increased 73%. The dynamic stress of the center control hole is the biggest to other control holes. The average of gas drainage volume in blasting holes is 55% larger than that of control holes.


As a principal measure of gas control, gas drainage is widely adapted in coal and gas outburst mines. Through strata pre-splitting blasting (it is also abbreviated for through strata blasting) is a new technology for increase drainage rate of gas. The blasting holes are drilled from other roadway and pass through multiple medium such as coal and rock, so it is more complex and difficult to analyze the blasting mechanism in the multiple medium than whole blasting holes in coal seams.

At present, most papers about through strata blasting introduce the application of blasting technology in control gas such as gas drainage along coal seam (Qiu & Gong 2009, Wang et al. 2008, Liu 1997), joint gas drainage and excavation (Guo et al. 2009, Cao & Yao 2009), rock cross-cut coal uncovering (Chen et al. 2009), treatment of blank area of drainage or other special site (Sun et al. 2010) and so on.

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