Numerical Simulation of Combined Water Injection in Deep Coal Seam and Its Field Application for Dust Suppression and De-stressing: A Case Study at Dongtan Coal Mine, China

Abstract

In order to achieve the best effects of water injection in coal seam, ANSYS software, which combines stress–strain relationship with computational fluid dynamics, was used to simulate the pressure and velocity field of coal seam under water injection pressures of 20 and 3 MPa for determining the optimal injection parameters. Simulation results showed that the high pressure could significantly enhance the wetting effect of coal, and that the water dilutive wet coal range under 20 MPa was about 1.93 times larger than that under 3 MPa. On this basis, the high and low pressure combined coal seam water injection technique was designed and applied to the #1305 fully mechanized top coal caving face in the Dongtan coal mine, and dust concentration and rock burst energy in the working face before and after water injection were statistically tested. It was found that the average reduction rates of total dust and respirable dust were 52.96 and 53.84% respectively, and that the released energy of a single rock burst was controlled within 105 J after adopting the combined technique. It is believed that the combined water injection technique has an obvious effect on dust control and rock burst prevention.