Research on the Control Mechanism and Technology of Coal Seam Stoping Roadway under Extremely Close Distance Fractured Soft Rock
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.
close distanceworking faceroof layinggrouting anchor cablesurrounding rock control
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