极近距离破碎软岩下煤层回采巷道控制机理与技术研究

Research on the Control Mechanism and Technology of Coal Seam Stoping Roadway under Extremely Close Distance Fractured Soft Rock

针对极近距离破碎软岩条件下巷道围岩控制难题,建立了下煤层开采回风巷围岩-顶板支护强度耦合力学模型,分析了巷道支护强度对极近距离破碎软岩响应安全阈值,基于双屈服应变硬化有限元模型揭示了柔性网均布分散采空区残余应力控制机理,提出了上煤层开采柔性网铺顶方案和下煤层回采巷道“护表强顶”方案相结合新技术体系。结果表明:层间距为0.9 m时,回风巷顶板支护强度安全阈值为0.2 MPa,需优化支护参数;数值模拟表明高强柔性网具有降低应力峰值及影响范围的正向作用,降低幅度分别为19.68%、45.3%;采用新技术体系后,破碎岩石胶结率高,顶板下沉量均小于50 mm,巷道返修率得到了有效控制。

Aiming at the difficult problem of controlling the roadway surrounding rock under extremely close distance fractured soft rock condition,a coupled mechanical model of the surrounding rock-roof support strength of the return air roadway in lower coal seam mining is established.The safety threshold value of the roadway support strength on the response of extremely close distance fractured soft rock is analyzed.Based on the double yield strain hardening finite element model,the residual stress control mechanism of the flexible mesh uniformly dispersed goaf is revealed.A new technical system combining the upper coal seam mining flexible mesh roof laying scheme with the lower coal seam stoping roadway"surface protection and strong roof"scheme is proposed.The results show that when the interlayer spacing is 0.9 m,the safety threshold value for the support strength of the return air roadway roof is 0.2 MPa,and further optimization of support parameters is needed;Numerical simulation shows that high-strength flexible mesh has a positive impact on reducing stress peak and influence range,with reduction amplitudes of 19.68%and 45.3%,respectively;After adopting the new technical system,the cementation rate of fractured rocks is high,the subsidence amount of the roof is less than 50 mm,and the repair rate of the roadway is effectively controlled.