Mechanism of water inhibiting gas outburst and the field experiment of coal seam infusion promoted by blasting

Gas outburst is a serious disaster in deep mining. In this paper, we first study the effect of water content on gas outburst, and found that increasing the water content of coal can significantly reduce the elastic modulus and uniaxial compressive strength, which is beneficial in reducing the peak stress concentration in the roadway and pushing the peak stress deeper. We also found that by increasing the water content of the coal seam, the firmness coefficient increases, while the initial speed of gas diffusion decreases simultaneously. Increasing the water content of the coal seam can also change the Langmuir adsorption constant of coal, reduce the a value of the limit adsorption capacity, increase the b value of the adsorption capacity, and reduce the amount of desorption gas in the coal. These studies indicate that increasing the water content of coal can significantly reduce the risk of gas outbursts. To increase the water injection volume, the technology of promoting coal seam infusion by blasting has been proposed. Blasting promotes equilibrium distribution in the stress field and generate new fractures, which promotes the water injection. In the 8th coal mine in the Pingdingshan coal field, the test results indicate that after loosening blasting, the water injection of a single borehole increased by an average of 54.6 times under the injection pressure of 3–7 MPa. The water content of coal is improved significantly, and the prediction index value of the gas outburst is reduced significantly. This technology is important for gas control in similar coal mines.