应力波扰动下深部层状煤岩体超低摩擦效应诱发冲击地压机理研究

The rockburst will more and more serious with deep mining. The mechanism and law has not still been clear. Based on friction characteristics in coal mines, anomalously low friction effect was introduced. The new rockburst type of anomalously low friction is presented. Thin soft coal seam was generated as repeadly strong disturbance of stress wave,sliding between layers occurre suddenly when stress disturbance and load reach the critical value,the velocity of sliding become nonlinear, friction force even anomalously low, produce anomalously low friction effect, and ultimately induce energy releasing. Based on layed coal and rock mass as research object, considering weak layer formation and the dynamic response action, anomalously low friction effect and rockburst will be linked from energy conversion view. Using the method of theoretical analysis and experiment, the theoretical models(simply supported beam model, cut shear beam model and the inter-layer failure model) will be established. The experiment will be made by white digital speckle observing deformation and failure of weak surface. The relationship among stress wave disturbance intensity, direction of propagation, occurrence of weak layer and the frictional resistance reducing will be obtained. The areas of anomalously low friction and the energy criterion will be determined. The mechanism will be revealed.

随深部开采，冲击地压愈趋严重，其研究远未达到机理清晰、规律明确的程度。根据大量现场观察到的摩擦破坏特征，引入超低摩擦效应，提出超低摩擦型冲击地压这一新命题。将深部冲击地压视为应力波扰动下形成次生薄软煤层，当扰动和荷载作用达临界值时，突然发生层间滑动，滑移速度非线性增大，摩擦阻力减弱、甚至极弱，产生超低摩擦效应，最终诱发积蓄能量释放的过程。以深部层状断续煤岩体为研究对象，首次考虑次生弱面形成及动力响应作用机制，从能量转化角度将超低摩擦效应与冲击地压联系起来，采用理论分析和实验研究相结合方法，建立超低摩擦效应模型（简支梁、剪切梁和层间失效模型），通过设计超低摩擦效应模拟试验，采用白光数字散斑技术观测次生弱面变形破坏，直至超低摩擦滑动失稳致灾全过程，获得应力波扰动强度、传播方向、次生弱面产状等与摩擦阻力降低间关系规律，圈定超低摩擦发生区域，建立深部超低摩擦型冲击地压发生能量判据，揭示其机理。

根据大量现场观察到的摩擦破坏特征，引入超低摩擦效应，提出超低摩擦型冲击地压这一新命题。项目以理论分析、实验研究和数值模拟相结合，按计划顺利完成。.理论分析方面：.建立了冲击载荷作用下考虑上覆岩层压力的深部冲击地压块体介质超低摩擦效应模型，推导得到了接触界面法向动力函数与位移函数解析表达式，给出了发生超低摩擦型冲击地压的冲击载荷临界值。考虑开采深度、冲击载荷强度和岩块尺寸对冲击地压发生机理影响，给出了深部冲击地压块体介质接触界面法向动力函数振动频率与深度关系，确定了冲击地压发生临界深度，首次从理论角度揭示了深部块系岩体超低摩擦效应诱发冲击地压机理。.实验研究方面：.研制了冲击载荷作用下块系岩体动力衰减实验装置，设计了冲击载荷作用下块系岩体动力衰减实验方案。通过改变冲击载荷强度，实验观测了块系岩体各层接触面及软弱夹层衰减特性，分析了有无夹层、夹层材料、夹层厚度等对块系岩体动力衰减影响规律，给出了超低摩擦型冲击地压发生优势接触面和优势方向，发现低频波作用更易导致超低摩擦型冲击地压发生。.数值模拟方面：.在实验基础上，以花岗岩块体模型为研究对象，采用FLAC-3D数值软件进行了垂直冲击作用下花岗岩块体模型动力响应模拟，与实验结果对照验证了采用FLAC-3D模拟超低摩擦型冲击地压可靠性。考虑两种加载条件，即垂直冲击和水平静力共同作用、垂直冲击和水平冲击共同作用下，对深部岩体超低摩擦效应进行了数值模拟，得到了模型中工作块体水平位移、法向力演变规律及块体模型垂直方向及水平方向应力的分布特征，从数值模拟角度分析了超低摩擦型冲击地压发生机理。.项目取得成果为深部冲击地压发生机理深入认识及其预测、防治提供了科学参考。