Study On Technology Of Gas Draining While Mining In Working-face

This paper studies on the application of the borehole control blast in solving the conundrum of methane excess and the random danger of coal-and-gas outburst when excavating coal on the low permeability and high gassy single coal seam. The article entirely researches its blasting mechanism and characteristics. And the article detailedly analyses its process during dynamite blasts in coal. The mathematical pattern of numerical value simulation of deep borehole control blast was established and the article simulates and analyses results by ANSYS, theoretically researches mechanism of stress discharging and permeability increasing after using borehole control blast and how the space between blasting hole, guiding hole, coupling quotiety and blasting hole diameter effect the post-blasting result. The paper gives the location of increasing permeability zone, reducing permeability zone and original permeability zone, and present the function describing the variety of permeability. At the same time, equation of gas flow field around borehole which draining and excavating for draining gas in constant and variational permeability coal seam was educed according to permeability theory of porous media. Computer programs were developed and numerical simulation of gas flow field around borehole was implemented. Moreover, industrial test was carried out in the mining of QinNan, layout parameters and optimum position of boreholes which draining and excavating for draining gas were determined, and the relations of amount of drainage power and number of boreholes were also set. The text was successful.The research shows that borehole control blast can reduce terra stress and gas pressure effectively, which can widely used to increase gas-draining quantity and avoid coal and gas outburst.