Study on Large Deformation Mechanism of Roadway with Close and Multi Coal Seam in Mining

In view of the serious local deformation of roadway in close coal seam mining, the seismic computed tomography (CT) and spatio-temporal evolution of microseismic were comprehensively investigated in this study. The static coal load and dynamic load disturbance were used to reveal the local large deformation mechanism of the mining roadway with coal pillars in close and multi coal seams. The result of this study showed that CT could accurately detect the static load stress concentration area, which was mainly located in the zone that was comprehensively influenced by overlying coal pillars, side abutment pressure, and pilot support pressure. The overlying coal pillar was the main influencing factor. In the Xinzhouyao mine, the static load stress concentration area detected by CT and the dynamic load disturbance concentration area detected by the microseismic spatio-temporal law were consistent with the roadway deformation position. According to the comprehensive theoretical model study, the main influencing factors of the local large deformation of the roadway were the static load stress concentration caused by the overlying coal pillar and the dynamic load disturbance caused by the fracture and slippage of the overlying coal pillar and roof under the influence of mining. The superposition of dynamic load disturbance and static load concentrated stress caused large deformation of the roadway, of which the static load stress concentration was the main influencing factor. The conclusions of this study can guide the determination of the risk zone of rock burst under similar conditions.