动静应力场对煤岩体气体吸附性能及断裂灾变诱发机制研究

In the high-gas coal seam of the deep coal mine, the mining engineering rock mass is inevitably bear the high geo-stress, gas pressure and the coupling effect of dynamic disturbing, the stress state is more complicated. The project focuses on the crack propagation characteristic and crack arrest condition of deep gas-containing coal rock by reproducing static stress and dynamic disturbance, using modified gas-sealing device. Based on the analysis of micro-structure evolution of gas-containing coal under different stress field loading, the crack propagation characteristics and the fracture toughness test on gas-containing coal specimens are carried out under different stress field loading and different initial gas pressure conditions, the characteristic of energy supply in the process of crack propagation in gas containing coal is comprehensive analysis by combine the theoretical and numerical simulation. The result is applied to establish the energy model for gas-containing coal crack propagation under multi-fields coupled. At the same time, combined with the analysis of the evolution of crack propagation and the micro analysis of fracture surface under different gas pressure and loading conditions, the fracture mechanism of the gas containing coal under multi-fields coupled stress field are reveals from the view of macro and micro, and then, exploration the conditions of crack arrest in gas containing coal. The fracture energy model and crack arrest parameters are tested and optimized by the study results above high-gas coal seams engineering examples. Furthermore, a comprehensive prevention and control theory and technology system of disaster by multi-fields coupled in deep high-gas coal seam are established. The project also can provide theoretical and test basis for the mechanism recognition of in deep high-gas coal mining disaster.

深部高瓦斯煤层回采岩体承受近场高地应力、高瓦斯压力及远场动力扰动耦合作用，其受力状态更为复杂。本项目利用改进的瓦斯密封装置和动静载加载设备实现耦合加载，重点研究深部含瓦斯煤裂纹扩展的孕育演化和止裂条件。基于不同应力场下煤岩细观结构演化分析，通过开展不同预应力场和瓦斯赋存状态条件下的冲击扰动裂纹扩展特性实验，利用理论及数值模拟研究方法，综合分析研究含瓦斯煤裂纹扩展过程的能量补给作用，建立含瓦斯煤气相和固相耦合材料裂纹扩展过程由近场力和远场力所构成的复合型应力场能量源模型；并结合不同应力环境下裂纹扩展演化过程及断口的微细观分析，从宏细观角度，揭示含瓦斯煤耦合应力场条件下断裂机理，探索影响含瓦斯煤裂纹止裂的条件；针对深部高瓦斯煤层回采实例，检验并优化裂纹断裂模型和止裂条件，继而形成近远场动静耦合致灾的防控理论和技术体系，为深部高瓦斯煤层开采含瓦斯煤岩动力灾害灾变机理的认识提供实验及理论依据。

在深部矿井中，煤炭开采处于高瓦斯压力和静应力的耦合作用下，同时还受到坚硬顶板破裂的动态载荷干扰。本项目通过单轴压缩、巴西圆盘和缺口半圆形弯曲载荷试验，使用了新开发的气体密封装置和RMT-150岩石力学试验机和分离霍普金森压力杆（SHPB），研究了初始气体压力为0.0、0.5、1.0和1.5MPa的四个水平的含瓦斯煤的动静态力学特性（即单轴抗压强度、抗拉强度和断裂韧性）。采用断裂力学的理论方法分析了气体吸附状态下裂纹的萌生特性。确定了不同初始气体压力下的断裂模式。结果表明，含瓦斯煤的单轴抗压强度、抗拉强度和断裂韧性随初始瓦斯压力的增加而降低。在高瓦斯压力下，含瓦斯煤在单轴压缩载荷下发生拉伸断裂。由于裂纹尖端有效应力的增加和裂纹强度的降低，含煤气体中的裂纹在小的外部载荷下扩展。含瓦斯煤在气体-静态-动态耦合负载下的动态压缩特性的研究，通过应力应变测量、碎片粒度分布统计和耗散能分析，在考虑不同气体压力和轴向静态预压应力的情况下，研究了含瓦斯煤动载荷试验的基本问题。波阻抗法用于定量描述损伤变量。分析了含瓦斯煤在耦合气体静动态载荷作用下的损伤变量。试验结果表明，耦合载荷下含瓦斯煤的动压缩强度随瓦斯压力的增加而降低，高瓦斯压力和轴向静应力的含瓦斯煤在动态载荷下更容易受到破坏，这可能导致深井高瓦斯煤层开采设计或支护设计的修改。