AN EXPERIMENTAL STUDY OF DEEP BOREHOLE PRE-CRACKING BLASTING FOR GAS PRE-DRAINAGE ON A MINE HEADING ROADWAY IN A LOW PERMEABILITY SEAM

Coal and gas outburst is the phenomenon that it sprays a large number of coal (rock) from coal and rock layer to the mining space within a very short time, during the coal mine underground mining process [1, 3–5].With the increase of mining depth, coal seam gas pressure and gas content increases significantly, and the risk of gas disaster also increases. Heading roadway in the outburst coal seam, the outburst risk must be eliminated in advance, with drillings through strata pre-drainage the coal seam gas, in order to make the coal seam pressure and gas content within the control range of roadway reduce to below the specified value of the provisions of coal and gas outburst prevention and treatment, however, because of low permeability seam in Huainan coal mine, gas pre-drainage effect is not good, leading to eliminate the outburst risk for a long time, thereby affecting the mine mining. In order to improve gas extraction in the control area of coal and seam, and improve the speed of the roadway excavation, in this paper, deep borehole pre-crack blasting was proposed, strengthening to increase the permeability of dug coal seam, and improving the gas drainage efficiency, to achieve the rapid safety excavation of outburst coal seam roadway.