层状岩石水-力耦合破坏机理与承压渗透特性研究

During mining above confined aquifers, mining-induced failure and discontinuous interface propagation and coalescence and failure in floor stratified rock may increase the floor permeability and form water conducted pathway, and induce water-inrush from floor. By the ways of theoretic analysis, numerical simulation and laboratory test, we analyze the failure mechanism and the confined permeability characteristics of stratified rock with different lithological combination and different interface dip under the condition of hydro-mechanical coupling. Using the confined permeability testing system for large-size rock, and introducing acoustic emission monitoring and location and network parallel electrical technology, we explore the deformation and strength characteristics, crack propagation and coalescence and failure characteristics, and the confined permeability evolution law during crack propagation and coalescence and failure. Based on the analysis of experimental data, and combined theoretic analysis and numerical simulation, we study the influence law of confining pressure, permeability water pressure, lithological combination, interface dip on the macroscopic failure mode of stratified rock and the variation of permeability coefficient during crack propagation and coalescence and failure, as well as establish the formulations of permeability coefficient that can reflect the relation between the failure mechanism and permeability evolution law, to disclose the confined permeability characteristics of stratified rock. The research achievements can help to reveal the water-inrush mechanism, and provide an important theoretical basis for the safety mining above confined aquifers.

承压水上煤层开采过程中在造成底板层状岩层采动破坏及不连续结构面扩展、贯通、破坏的同时，增大了底板岩层的渗透性，形成突水通道，诱发工作面底板突水。本项目采用理论分析、数值模拟和室内实验相结合的方法，对不同岩性组合、不同界面倾角的层状岩石水-力耦合破坏机理与承压渗透特性进行研究；利用大尺寸岩石承压渗透试验系统，并引入声发射监测定位和网络并行电法技术，探索水-力耦合作用下层状岩石的变形与强度特性、裂隙扩展贯通与破坏特征以及裂隙扩展-贯通-破坏过程中的承压渗透演化规律；在分析试验数据的基础上，结合理论分析和数值模拟等方法和手段，研究围压、渗透水压力、岩性组合、界面倾角对层状岩石宏观破坏形式及裂隙扩展、贯通直至破坏过程中渗透系数变化的影响因素，建立反映层状岩石水-力耦合破坏机理与渗透性演化的渗透系数表达式，揭示层状岩石承压渗透特性。研究成果有助于揭示底板突水机理，为承压水上安全带压开采提供理论依据。

承压水上煤层开采过程中在造成底板层状岩层采动破坏及不连续结构面扩展、贯通、破坏的同时，增大了底板岩层的渗透性，形成突水通道，诱发工作面底板突水。项目以授权“制备含不同倾角结构面岩石试样的切割装置及使用方法”、“承压岩石破坏失稳过程与动态渗透特性试验装置及方法”2项发明专利为基础，对不同岩性组合、不同界面倾角的层状岩石水-力耦合破坏机理与承压渗透特性进行试验研究。揭示了水-力耦合作用下层状岩石在压密阶段其渗透性随应力的增大而略有降低或变化不大，在弹性阶段其渗透性变化不大，在塑性阶段其渗透性先缓慢增大而后急剧增大，在破坏初期阶段其渗透性进一步增大，但随着破坏裂隙的压缩闭合，渗透性急剧减小并趋于稳定。阐明了层状岩石破坏强度随承压水压的增大而减小，随组合倾角的增大而减小，随围压的增大而增大；破坏强度峰值对应的应变随承压水压的增大而减小，破坏后的残余强度随承压水压的增大而略有提高；层状岩石破坏后的渗透系数峰值随承压水压的增大而增大，随组合倾角的增大而增大，随围压的增大而减小；随承压水压的增大，层状岩石破坏后的延性性质降低，脆性性质增强；层状岩石承压渗透过程中累计声发射振铃计数与累计声发射能量随承压水压的增大而减小，随组合层状倾角的增大而减小，随围压的增大而减小；围压作用下组合层状岩石在倾角为0°、15°和30°时，以剪切破坏为主；随组合倾角增大（45°和60°），组合层状岩石由剪切破坏逐渐转化为界面滑移破坏。初步获得围压、承压水压、岩性组合、界面倾角对层状岩石宏观破坏形式及裂隙扩展、贯通直至破坏过程中渗透系数变化的影响规律及渗透系数与承压水压、界面倾角、围压的定量关系。另外，为应用于煤层底板突水预测，建立了水平、倾斜层状岩板模型，采用理论分析、数值模拟方法，分析了水平、倾斜层状岩板力学特性、突水危险区域，推导了倾斜层状岩板失稳力学判据。研究成果有助于揭示底板突水机理，为承压水上安全带压开采提供基础依据。