断层应力转向对含瓦斯煤体损伤失稳作用机制及应用研究

The majority of especially super-huge coal and gas outbursts in our country are closely related to the fault structure, while the fault has a rotation effect on the original rock stress-state. The superimposed stress of mining disturbance under fault environment is a complex stress path evolution with stress rotation. Meanwhile, the stress rotation give the damage and instability of containing gas coal mass of a controlling effects, there are some deficiencies in the above studies. Therefore, the proposed project is put forward. A combination of research methods of theoretical research, numerical simulation, experimental study and field test is applied in this project. The distribution feature of the rotation stress of fault original rock and its formation mechanism are revealed; on this basis, the evolution law of superimposed stress caused by mining disturbance is obtained to provide the mechanical path for laboratory study; the mesoscopic damage-destruction evolution of containing gas coal mass under the stress rotation condition is investigated, the uncoaxial constitutive model of containing gas coal mass under the rotation stress is established, and finally the coupling model of coal stress-damage-seepage under the action of fault rotation stress and coupling superposition of mining disturbance is built to reveal the action mechanism of stress rotation on the damage and outburst/instability of containing gas coal mass. The research findings of this project can provide theoretical basis for prevention and control of coal and gas outburst in fault zone and other dynamic disasters under similar circumstances.

我国发生的特大型煤与瓦斯突出多与断层构造密切相关，断层对原岩应力具有转向作用，进而断层环境下采掘扰动叠加应力演化是包含有应力转向的复杂应力路径，而应力转向对含瓦斯煤体损伤失稳又具有控制作用，目前针对上述研究还存在不足。因此拟申请项目采用理论研究、数值模拟、实验研究和现场测试相结合的研究方法。研究断层原岩转向应力的分布特征，并揭示其形成机制；在此基础上，获得采掘扰动形成的叠加应力的演化规律，为实验室研究提供力学路径；研究在应力转向环境下含瓦斯煤体细观损伤破坏演化，建立应力转向下含瓦斯煤体非共轴本构模型，并最终构建断层转向应力和采掘扰动耦合叠加作用下含瓦斯煤体应力-损伤-渗流的耦合模型，揭示应力转向对含瓦斯煤体的损伤及突出失稳作用机制。本项目研究成果可为断层煤与瓦斯突出防治以及类似背景下的矿井动力灾害防控提供理论基础。

为深入研究煤与瓦斯突出机理的重大难题，针对断层构造等地质背景下煤与瓦斯突出，运用综合的研究方法，针对断层对地应力的转向作用、采掘扰动形成的叠加应力的演化规律以及在此作用下含瓦斯煤体损伤破坏渗流机制，最终揭示应力转向对含瓦斯煤体的损伤及突出失稳作用机制开展多尺度，多层次的研究。采用现场实测和理论分析，获得了由于断层带分区煤岩力学特性的差异造成了应力在断层带中的传递转向，建立了转向计算模型；其次通过理论分析与数值模拟，获得了在不同工况条件下采掘工作面应力集中区应力旋转呈现最大主应力垂直掘进头，并导致煤岩界面间剪切应力增强效应，尤其是在断层带和构造软煤带变化趋势更显著，在细观上，由于构造煤颗粒力链在应力作用下产生局部化变形剪切带，在剪切带内外呈现不同的主力链方向偏转，揭示了应力偏转的宏观效应的细观机制。应力旋转导致构造煤体的在不同应力环境下呈现不同的损伤行为，呈现不同单剪切带与共轭剪切带特征，在此基础上，开展的含瓦斯煤的渗流实验，建立考虑损伤特性的渗透率突变模型。在断层带掘进过程中，含瓦斯构造煤颗粒在应力作用下呈现高耗散特性，尤其在应力主轴旋转作用下，使得优势通道开启，应变能转化诱导含瓦斯煤体产生高孔隙空间，并使得煤颗粒急速解吸富集瓦斯能，为煤与瓦斯突出奠定瓦斯能基础。上述研究为构造煤瓦斯抽采和防突技术开发奠定理论基础。