Field test research on gas migration law of mining coal and rock

The fractures in coal and rock mass are the main channels of gas seepage, and understanding the gas migration law during mining is the precondition of gas control. The long-term in-situ monitoring of the abutment pressure, fracture networks and gas-flow in front of a mining face was carried out and the 1-D connectivity ratio of boreholes were calculated. The results showed that under the influence of mining, the fracture networks developed to the depth of rock stratum, and as far-field gas seepage channels, far-field gas continuously supplied the near-field gas. The gas flow in front of the mining face have undergone two stages of evolution from initial value to peak value, and then to a stable value. The 1-D connectivity ratio the abutment pressure about 5 to 10 m. The 1-D connectivity ratio reflected the dergree of coal and rock fracture penetration caused by mining, and the area with the highest gas extraction efficiency was the transition zone from peak abutment pressure to residual pressure in coal seams.