近距离煤层过空巷底板破坏机制及支护对策

Failure mechanism and supporting countermeasures of close distancecoal seams passing through goaf roadway floor

近距离煤层群开采,当工作面下部临近煤层含有空巷,为解决工作面过空巷时综采机头塌陷,空巷顶板出现局部坍塌和区域冒顶等情况,采用理论分析、数值模拟及现场监测等综合技术手段对近距离煤层群开采的工作面过空巷底板变形破坏机制进行了深入研究。首先对工作面过空巷时底板稳定性进行了理论分析,对比了空巷支护与未支护条件下分别能承受的支架工作阻力;然后采用FLAC3D软件模拟了工作面过空巷时底板变形破坏塑性区范围和应力分布情况,结果表明空巷采取木垛支护情况下底板变形破坏范围和程度均有所降低。理论分析与数值模拟基础上,工程现场对空巷区域采用“#”字型空心木垛加强支护措施,工作面回采过程对顶板位移及应力分别进行监测,顶板下沉量不超过4 cm,最大压力不超过5 kN,保证了工作面安全顺利回采。可为相关工程类似条件下工作面过空巷回采提供参考和依据。

In close-range coal seam group mining,when the coal seam near lower part of working face contains goaf roadway,in order to solve collapse of fully-mechanized mining head when working face passes through goaf roadway,the roof of goaf roadway appears partial collapse and regional roof collapse,etc.A comprehensive technical approach,including theoretical analysis,numerical simulation,and on-site monitoring,was used to conduct in-depth research on deformation and failure mechanism of working face through goaf roadway floor in close range coal seam group mining.Firstly,the stability of floor when working face passes through goaf roadway floor is analyzed theoretically,and the working resistance of support under condition of supporting and not supporting is compared respectively.Then FLAC 3D software is used to simulate plastic zone range and stress distribution of floor deformation and failure when working face passes through goaf roadway.The results show that the deformation and failure range and degree of floor are reduced when the goaf roadway is supported by wood pilings.On the basis of theoretical analysis and numerical simulation,the engineering site adopts the“#”shaped hollow wood stack to strengthen the supporting measures in the goaf roadway area,and the roof displacement and stress are respectively monitored during the mining process of the working face.The roof subsidence is less than 4 cm,and the maximum pressure is less than 5 kN,which ensures the safe and smooth mining of the working face.It can provide reference and basis for mining through goaf roadway under similar conditions.