Study On Permeability Improvement And Gas Extraction Technology Of Deep Hole Pre-splitting Blasting In11-2Coal Of Panyidong Coal Mine

In the process of coal mining, gas disaster has been one of the main disasters threatened to coal mine safety production. At present, the mine gas extraction is considered to be the most fundamental technical way to prevent coal and gas outburst. However, with the increase of mining depth, it has brought new problem for gas extraction work. The increase of mining depth results in increasing gas content and pressure of the coal seam, and sharply decreasing permeability, gas extraction effect is seriously affected. Therefore, improving permeability of coal seam has become an important way to realize safety efficient production of the coal mine.In this paper, combined with the methods of theoretical analysis, numerical simulation and field experiment, deep hole pre-splitting blasting pressure relief and permeability improvement effect mechanism is studied. Firstly, the theory of gas storage and flow in coal seams are analyzed; Secondly, pressure relief and permeability improvement mechanism of deep hole pre-splitting blasting technology is analyzed, it is concluded that after the explosion, the cross-shaped fracture network is produced in the coal surrounding the blasting hole; and during the process of fracture development, detonation stress wave and detonation gas effect play the main effect, control hole provides auxiliary free surface, and coal gas pressure further promotes the development of coal fractures; Research shows that deep hole pre-splitting blasting technology can make coal fractures increased, and permeability improved, effectively prevent and eliminate the risk of coal and gas outburst. At the same time, mathematical models of deep hole pre-splitting blasting pressure relief and permeability improvement effect in the coal seam are established, with ANSYS/LS-DYNA software numerical simulation, stress distribution and fracture development of coal at different time are simulated. When the spacing of two blasting holes is6～7m, a large number of fractures communicated with each other can be produced after the blasting, and forming fracture network, greatly increasing permeability of the coal. Finally, in the1252(1) track crossheading bottom roadway of11-2coal of Panyidong coal mine, the field industrial experiment study shows that pressure relief and permeability improvement effect of deep hole pre-splitting blasting is obvious, the effective pressure relief radius can be up to4m, gas extraction volume and gas extraction rate are greatly improved, and it has an important social value and economic benefit.