煤层采掘活动引起断层活化的微震前兆试验研究

The discontinuous structure fault controls the deformation, damage, and mechanical properties of coal-rock mass. The interaction between the structure and coal mining activities has an essential effect on fault reactivation. Based on the research background of microseismic monitoring and early-warning of fault reactivation, true-triaxial load-unload and dynamic-static experiments, which consider the three key factors “fault, mining-induced stress, and dynamic stress of mine tremor”, will be conducted on the coal-rock mass containing fault plane. The stress-strain constitutive and strain energy evolution law will be studied for the process of deformation-damage and instability on the coal-rock mass containing fault plane, and the criteria of fault reactivation will be proposed using stress and strain energy. Regarding this as the cutting point, the transforming relationship will be investigated between strain energy and stress-strain and acoustic emission (AE). Regarding the micro-rupture corresponding strain energy release and stress drop characteristics as the bridge, the techniques of digital photogrammetry, AE monitoring, and passive acoustic wave CT will be adopted to study the internal relations and laws between the AE time-space-magnitude evolution parameters and acoustic wave velocity and the stress-strain and strain energy. Combining with the in-situ monitoring, microseismic precursors of fault reactivation will be recognized essentially. On this basis, the early-warning indexes and their criteria will be improved and developed, including bursting strain energy, microseismic time-space-magnitude information, and seismic wave velocity CT. The expected outcomes of our proposal may provide some useful references for the effective monitoring and early-warning and pertinence prevention of rock burst in the fault mining regions.

断层不连续结构控制着煤岩变形、破坏及力学性质，该结构与煤层采掘活动之间的相互作用是影响断层活化的关键。本项目以断层活化的微震监测预警为研究背景，围绕煤层采掘活动引起断层活化的“断层、采动应力、矿震动载”三个关键因素，开展含断面煤岩体的真三轴加卸载动静组合试验，研究含断面煤岩体变形损伤失稳过程的应力应变本构和变形能演化规律，提出断层活化的应力及变形能判据；以此为切入点，探索变形能与应力应变、声发射之间的转化关系；以微破裂对应的变形能释放、应力降特性为纽带，采用数字照相量测和声发射监测及其声波被动CT技术，研究声发射时空强演化参量和声波速度与应力应变、变形能之间的内在联系和相关规律；结合现场微震监测，从本质上认识断层活化的微震前兆信息；在此基础上，完善和改进冲击变形能、微震时空强多维信息、震动波速度CT预警指标及其判别准则。研究成果能够为断层区域冲击地压的有效监测预警和针对性防治提供有益参考。

断层作为煤层采掘过程中普遍存在的一种地质构造，其独特不连续结构控制着煤岩的变形、破坏与力学性质，该结构与煤层采掘活动之间的相互作用是断层活化及其诱冲的关键。.项目通过调研总结煤层采掘活动与断层赋存状态之间的概念模型，提出了采动应力主导和矿震动载主导型两种断层活化类型的力学机制，建立了煤层采掘活动诱发断层活化的应力及变形能判据，以及变形能与应力应变、声发射之间的转化关系，构建了基于微震重构的冲击变形能预警指标；设计并开展了采动应力主导型断层活化类型的断面试样瞬间卸载与加卸载实验、以及矿震动载主导型断层活化类型的断面试样动静载组合实验，研究了含断面煤岩体灾变破坏过程的宏观破坏特征、应力应变、声发射时空强演化、声波速度、断面滑移形变等参量之间的内在联系，发展了微震时空强多维信息和震动波速度CT预警指标。.研究结果表明，断层冲击地压的发生由断层与顶板结构双重作用形成的断层煤柱高静载与采动应力或矿震动载主导型断层活化动载叠加诱发，其中，断层活化动载由静载为主的局部解锁、等效劈裂破坏和动载为主的超低摩擦效应组成，并与断层面粘结力、摩擦角、倾角、最小主应力、孔隙压力、断层围岩抗拉强度等因素密切相关；以冲击变形能、震动波CT反演表征的应力环境、微震时空强等15种特征参量作为模型输入，混淆矩阵与高斯隶属判别函数联合的模糊综合评判模型作为智能融合运算的微震多参量综合智能预警模型，可实现以客观数据驱动为主的指标权重自适应智能实时调整，以及以无、弱、中、强四个冲击危险等级标识的分级概率与综合智能预警。.项目研究成果在河南义马跃进煤矿25110、陕西彬长胡家河煤矿402103、山东朝阳煤矿3206等工作面开展了检验与示范应用；相关理论技术体系也被其它类似条件下的煤及非煤矿山采用，对于断层区域储层改造、修建水电硐室、交通隧道等领域也具有积极意义，社会经济效益显著。