海下强膨胀软岩动压巷道恒阻让压耦合支护技术研究

Constant resistance coupling support technology of dynamic pressure roadway under sea with strongly swelling soft rock

为解决北皂煤矿强膨胀软岩回采巷道在超前动压力作用下引起的开挖初期变形量大、全断面持续大变形、U型钢支架破坏严重等问题,采用微观物化分析、地应力测试等手段,揭示围岩强度低、强膨胀性、强吸水软化、围岩应力四周来压、支护与围岩变形不耦合的失稳机制,提出恒阻锚杆支护方法,并揭示恒阻锚杆可通过高阻、高预紧力、可变形让压结构特征支护强膨胀软岩的支护机制,最终提出锚梁结构强化顶板+恒阻锚杆加固两帮+注浆锚固支护底角的恒阻让压耦合支护方案,并采用数值模拟进行支护效果对比分析。现场试验表明:恒阻让压耦合支护能够较大幅度减小巷道围岩变形量和超前动压影响范围,其中变形量最大282 mm,超前动压影响距离70 m,分别较普通螺纹钢锚杆+锚梁支护变形量减小64.8%、动压影响距离减小10 m,较U型钢架棚壁后浇筑混凝土支护变形量减小54.7%,动压影响范围减小20 m。在同类软岩巷道中具有良好的推广应用价值。

To solve the problems such as large deformation at the initial stage of excavation,large deformation of the whole section and serious destruction of U steel support caused by the dynamic pressure in the strong swelling soft rock roadway in the Beizao coal mine,the instability mechanism of low strength,strong expansion,strong water absorption softening,surrounding rock pressure,non coupling between support and surrounding rock deformation is revealed by means of microscopic physical analysis and in-situ stress test.The constant resistance bolt support method was put forward,and the support mechanism of the constant resistance anchor bolt can be supported by the high resistance,high pre tightening force,deformation and pressure release structure to support the strong swelling soft rock.Finally constant resistance supporting scheme for pressure coupling consisted of the anchor beam structure strengthening roof ＋ constant resistance anchor reinforcing for two sides ＋ grouting anchorage reinforcing bottom was proposed.Numerical simulation is used to compare and analyze the supporting effect.The test results show that the constant resistance pressure coupling support can greatly reduce the deformation of roadway surrounding rock and the influence range of leading dynamic pressure,the maximum deformation is 282 mm,ahead of the dynamic pressure distance is 70 m.Compared with the ordinary steel bolt and anchor beam support deformation,the deformation reduced by 64.8% and the dynamic pressure influence distance reduced by 10 m,compared with the U type steel frame shed,the deformation reduced by 54.7%,and the dynamic pressure influence range decreased by 20 m.It has good popularization and application value in similar soft rock roadway.