Dynamic response of coal seam and roadway during coal and gas outburst

To further study the mechanism of coal and gas outburst and understand the process of dynamic disaster, the multi-field coupling testing system for dynamic disaster in coal mine was used. Based on the actual situation of the working-face of K1 coal seam in Shuijiang Coal Mine, Chongqing, China, the dynamic response test of coal seam and roadway during the outburst process with a predetermined gas pressure of 2.0 MPa was carried out. The gas pressure and temperature of coal seam, the motion characteristics of two phase flow, the impact force and temperature of roadway during the outburst were investigated. The findings indicate that the change of the gray value of the image information in the outburst process can well reflect the kinematic characteristics of coal powder, and the pulverized coal has vibration characteristics and secondary acceleration characteristics. The secondary acceleration of pulverized coal means that the energy is concentrated and the drag force is increased. There is a choking phenomenon in the process of gas pressure drop in coal seams, which is represented by the periodic fluctuations of gas pressure, and this phenomenon is the essence of the vibration characteristics of outburst. The larger the geo-stress value, the faster the gas pressure and the temperature decrease, and the temperature change is consistent with the gas pressure change. During outburst process, the temperature drop of coal seam reaches 8℃. After the outburst is triggered, the weak disturbance is mainly in the early stage of the roadway, and the superim-posed disturbance appears at 5 044 mm from the working plane. Then, the disturbance will periodically rise and fall until the energy decays to zero. In the later stage of outburst, although the gas expansion energy is not enough to throw the coal powder out of the cavern, there is still a large amount of gas desorbing continuously. Therefore, the development stage of outburst should also include the continuous desorption and motion of the later single-phase gas. © 2020, Editorial Office of Journal of China Coal Society. All right reserved.