Research on stability control technology of surrounding rock along goaf roadway with water intrusion in isolated island working face

At present, there are few researches on the reasonable coal pillar design under the condition of accumulated water weakened surrounding rock in the goaf of isolated island working face. Only simplified analysis or theoretical researches are conducted from one aspect such as the influencing factor of weakened bearing strength of coal pillar by accumulated water, simplified model of conventional stress of coal pillar, laboratory determination of accumulated water weakened coal pillar strength, etc. The effect of surrounding rock control along goaf roadway is poor. In order to solve this problem, the I020908 return airway of Qipanjing Coal Mine of China Energy Mengxi Coal Chemical Co., Ltd. is studied as the engineering background. In order to solve the problem of serious deformation of the surrounding rock along the goaf roadway under the condition of accumulated water weakening in the goaf of the isolated working face, the physical and mechanical parameters of the coal rock mass under the two conditions of dryness and water absorption saturation are determined by indoor physical and mechanical experiments using laboratory measurements and numerical calculations and analysis methods. Based on the measured parameters, FLAC3D numerical software is used to establish a numerical calculation model for the weakening of surrounding rock, which analyzes the evolution law of lateral support stress and the distribution characteristics of plastic zone in the surrounding rock in the roadway under the condition of accumulated water in the goaf. The mechanical model of accumulated water weakened coal pillar is established and a reasonable coal pillar width of 6-12 m under the accumulated water condition is determined. In order to solve the problem of roof falling and rib spalling caused by the water intrusion of the coal pillar of the return airway, a technical scheme for the stability control of surrounding rock along goaf roadway with water intrusion in isolated island working face is proposed. When the width of coal pillar is 6 m, the anchor cable reinforced support of the roadway can effectively control the large deformation of the surrounding rock of the roadway. The deformation of the surrounding rock of the roadway tends to be stable within 52 d after using the reinforced support. The maximum displacement of the roof and floor is about 200 mm, and the maximum displacement of the two sides is about 130 mm, which is 85.6% lower than the displacement of the surrounding rock under the original support condition. The control effect of the surrounding rock of the roadway is better.