关键词: CO2相变致裂, TNT当量转化, 地应力, 爆破参数, 工程试验

Abstract: To increase the permeability of coal seams and improve the gas extraction rate, based on the TNT equivalent conversion of CO2 airburst energy release, LS-DYNA software was used to analyse the influence of blasting parameters (load volume, peak pressure relief and fracture hole diameter) and the effect of geostress on the effect of liquid CO2 phase change fracturing, and liquid CO2 phase change fracturing engineering tests were carried out on the working face of 109 in a mine. The simulation results show that the effect of liquid CO2 phase change fracturing is positively correlated with the change of load volume, peak pressure and fracture hole diameter, and negatively correlated with geostress, and the load volume and fracture hole diameter should not be too large; the test results(3.62m) show that the effective fracture radius of the coal seam is close to the simulation results(3.47m), which verifies the reliability of the numerical model of blasting, and the increase of penetration of the coal seam by applying liquid CO2 phase change fracturing technology. After applying the liquid CO2 phase change fracturing technology to increase the permeability, the permeability coefficient of the observation holes at a distance of 1m from the fracturing holes increased by 34 times, the intensity of gas outflow from the observation holes at a distance of 2.5m from the fracturing holes increased by 3.57 times and the intensity of attenuation was reduced by 63.16%, and the average concentration of gas extraction from the observation holes at a distance of 1m-1.5m from the fracturing holes was increased by 64.38%.