深部下组煤柔性充填开采防治高承压突水机理研究

The key of sustainable development is to mine lower coal group of Huabei permo-carboniferous in Mid-Eastern China, but normal caving method is easily to induce water inrush. The subject aims to study mechanism of flexible backfill mining to prevent and control high confined water inrush. Firstly, bearing capability and deformation performance test and stress-passing characteristic test of different proportion filling materials in different confining pressure and laboratory simulation test are carried out in order to study roof-filling-floor flexible support effect, evolvement law of additional stress field and floor load effects. Secondly, additional stress field distribution and prediction model of flexible backfilling floor strata under the condition of different geological and mining is established, in order to gain dynamic changing law of surrounding strata release-pressure and floor strata pressure balancing affected by mining. Thirdly, study straining motion characteristics of mining overburden and floor strata under the condition of different filling parameters, effect characteristics of floor strata stress and development law of water flowing fractured in high stress flexible backfilling. Lastly, force analysis model of roof-filling-floor coupling release-pressure and floor strata pressure balancing condition with high stress-strong seepage in the deep mine is established. Condition parameters of surrounding strata release-pressure, floor strata load-transmitting and water inrush mutation conditions with flexible backfilling are given for different type of floor water inrush. The research is of great theoretical and practical significance to mine lower coal group safely.

华北深部石炭-二叠纪下组煤开采是我国中东部煤矿可持续发展的关键，常规开采方法容易诱发底板突水。课题以采场柔性膏体充填防治高承压突水机理为研究目标，首先进行不同围压、配比充填材料承载-变形、恒载和冲击动载传力特性及室内模拟试验，分析柔性充填采场顶板-充填体-底板柔性支撑效应、附加应力场演化及底板荷载效应；其次根据不同地质采矿条件，建立柔性充填采场底板岩体附加应力场分布特征及预测模型，获得采动围岩让压和工作面底板均压状态及动态演化规律；再次研究不同充填参数条件下采动覆岩及底板岩层形变运动特征，高应力柔性充填条件下底板岩体受力影响状态及导水裂隙发育演化规律；最后建立深部高应力-强渗流条件下顶板-充填体-底板耦合让压及实现底板基本均压状态力学分析模型，针对不同高承压突水类型给出柔性充填围岩让压及底板均压、突水突变条件参量。课题的研究对实现华北深部石炭-二叠纪下组煤安全开采具有重要的理论及现实意义。

华北石炭-二叠纪深部下组煤开采是我国中东部煤矿可持续发展的关键，由于应用于浅、中部煤层开采底板注浆加固技术在深部下组煤开采时底板注浆改造效果不佳而不得不谋求其它的方法。柔性充填技术作为一种可行的开采方法，为进一步揭示防治底板高承压突水机理，项目首先开展了柔性充填材料配比、单轴、三轴压缩试验，获得了柔性充填材料承载-变形效应及峰后塑性强化特性，其次基于弹塑性力学和塑性滑移线场理论，建立了柔性充填采场底板结构力学模型，分析了底板岩体在采动应力和水压联合作用下应力分布特征，得出了底板塑性区破坏范围为12.65m；再次采用自行研制的底板突水模拟实验系统，研究了底板应力场、位移场、水压力场、断层带附近水压、导升高度及裂隙扩展情况，揭示了底板岩层破断判距和断层上下盘应力变化特征，获得了完整底板承压水导升高度为1.9cm，隐伏断层附近底板承压水最大导升高度为12.4cm；然后采用FLAC3D5.0对柔性充填不同充填参数进行数值模拟，得出开切眼前方垂直应力呈现蝶状分布特征，超前应力集中系数为1.48，充填体最大应力11.5MPa，底板最大渗流速度0.0000125m/s，最大导升高度达到11.21m，底板最大破坏深度为7m，隐伏断层上方最大破坏高度为4m；最后采用双端封堵侧漏技术对某矿深部下组煤柔性充填开采与相邻工作面垮落法开采底板破坏深度进行了实测对比，得出柔性充填开采底板最大破坏深度为6.33m，长壁垮落法开采底板破坏深度36.5m，柔性充填开采矿山压力对工作面底板破坏深度仅为垮落法开采的17.3%。鉴于目前“三下一上”开采规范缺少相关充填开采防治高承压突水岩层控制理论及底板破坏深度预计公式，本项目研究成果丰富了充填开采底板突水岩层控制理论，为深部下组煤柔性充填开采底板破坏深度合理确定提供了依据。