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Research on the Deformation Characteristics and Support Technology of a Bottom Gas Extraction Roadway under Repeated Interference

Taking Pingbao Coal Mine as the engineering background, the stress distribution, surrounding rock displacement, and plastic zone distribution characteristics of a bottom gas extraction roadway are simulated by FLAC3D under multiple disturbances. The mining disturbance due to the overlying coal seam is obtained: the deformation of the roof subsidence and lower rib closure of the bottom gas extraction roadway are larger than the floor heave and upper rib closure, respectively. According to the mechanical analysis of the bottom gas extraction roadway, the equations for calculating the displacement at each point on the surface of the bottom gas extraction roadway and the methods for calculating the maximum displacement, the maximum normal stress, and the maximum shear stress are obtained to reasonably explain the deformation of the bottom gas extraction roadway under multiple disturbances. Then, the bolt-mesh-anchor and ladder beam support mode are designed. After onsite observation of the bottom gas extraction roadway of the 12030 coal mining face of the Pingbao Coal Mine, it is concluded that the deformation characteristics of the bottom gas extraction roadway basically conform to the abovementioned equations and that the support is effective. This paper can provide a reference for the optimization of bottom gas extraction roadway positioning, the determination of support parameters, and the deformation prediction around a bottom gas extraction roadway under similar conditions.