高压水射流增透诱发高瓦斯煤体喷孔失稳机制研究

Deep low permeability coal seam gas control is a worldwide problem, water jet technology is widely used in underground drainage and gas outburst prevention. However, easily induced in the engineering application problems of boreholes strongly spray and gas concentration overrun tunnel construction. The key issue is to solve coal body instability induced by inoculation and mutation mechanism during water jet slotting under high gas and stress conditions. This project is limited under the condition of increasing permeability of coal containing gas jet deformation damage characteristics based on the consideration of the maximum principal stress angle, and increasing permeability of weak plane length and hardness of coal and other factors, described around the antireflective weak face response of stress damage seepage; a water jet nozzle ar soft coupling mechanical loss the stability analysis model, expanding influence rate of stress variation rate and gas gradient force, to clarify the water jet nozzle and dig coal instability process; finally, the damage of coal rock under impact stress strain and fracture dynamic response based on the establishment of coal rock breaking transient load along the axial fitting function the distribution of water jet jet, revealing ar induced mutation effect of orifice start, explore the scope of time and space and the criterion of orifice occurred induced. The research results can provide basic theoretical guidance for the prevention and control of the borehole spray in the engineering of the coal mine water jet slotting technology.

深部低渗煤层瓦斯治理是世界性难题，水射流增透技术是普遍采用的井下抽采与突出防治方法，但存在易诱发抽采钻孔强烈喷孔、施工巷道瓦斯浓度超限的工程应用难题，亟需解决高瓦斯、高地应力条件下水射流增透过程中煤体失稳孕育与突变诱发机制这一关键课题。本项目基于受限条件下水射流增透含瓦斯煤体变形损伤特性，考虑最大主应力与增透弱面夹角、弱面长度及煤硬度等因素，描述增透弱面周围的应力-损伤-渗流响应；建立水射流增透软煤喷孔失稳的耦合力学模型，分析扩挖速度率对应力变化率及瓦斯梯度力的影响，阐明水射流扩挖软煤喷孔失稳的孕育过程；最后，基于煤岩受冲击损伤的应力-应变及断裂动态响应，建立煤岩破断瞬态卸荷力沿射流轴向分布的拟合函数，揭示水射流增透喷孔启动的突变诱发效应，探讨诱发喷孔发生的时空范围与判据。研究成果可为我国煤矿水射流增透技术工程应用中的喷孔防控提供基础理论指导。

水射流增透技术是深部低渗煤层瓦斯治理普遍采用的井下抽采防治方法，但存在易诱发抽采钻孔强烈喷孔、施工巷道瓦斯浓度超限的工程应用难题，亟需解决高瓦斯、高地应力条件下水射流增透过程中煤体失稳孕育与突变诱发机制这一关键课题。本项目围绕水射流增透含瓦斯煤力学响应特性，高瓦斯软煤喷孔失稳的孕育机制以及高压水冲击破断的突变诱发效应等三方面研究内容，通过实验室试验与数值模拟分析了水射流冲击致裂煤体应力-应变-损伤特性，以及缝槽弱面条件下裂隙演化规律；理论推演与现场试验研究了水射流增透导致煤岩失稳的内部应力耦合与外部突变诱发机制；搭建受载条件下高压水射流冲击煤岩的瞬态破断特性研究平台，试验分析了煤岩受冲击损伤的应力-应变及断裂动态响应特性。通过本项目研究，发现并总结了切槽面与载荷夹角、切槽数量、切槽间布置方式等切槽参数对煤岩损伤-渗透率影响的规律，建立了水射流切槽开挖诱导煤岩喷孔发生的地应力、瓦斯梯度力及瞬态卸荷力综合作用理论判据条件，现场验证了判据临界条件的合理性，确定了诱发喷孔失稳的关键影响因素；建立了试件破裂情况表征方法，试验总结了水射流冲击煤岩瞬态破断特性与受限应力、射流参数的关系，支撑了水射流切槽诱导喷孔失稳发生判据理论假设。项目研究共发表科技论文5篇，其中EI/SCI收录3篇，授权发明专利4项，获省部级三等奖2项，成功立项国家标准编制并获批计划1项；培养硕士研究1人、职称晋升2人，项目负责人获省部级人才计划支持及省部级荣誉表彰。研究成果能够为我国煤矿水射流增透技术工程应用中的喷孔防控提供基础指导，成果支撑的高压水射流冲击致裂增透技术被列入《煤矿安全生产先进适用技术装备推广目录（第三批）》，已在多个矿区推广并取得良好的应用效果。