厚硬岩层破断冲击扰动含瓦斯煤动力响应特征与突出灾变机制

In China, more than 50 % of the mining areas exist thick-hard rock strata in the roof in the coal measures strata, where the large area mining of underlying high gassy coal seams often leads to instability and rupture of the thick-hard rock strata, forming impact effect directly on the underlying gassy coal, and causing the increasing of the coal and gas outburst risk. By taking three different rank underlying gassy coal with original moisture as the research objects, the impact effect induced by instability and rupture of the thick-hard rock strata is considered as the external conditions, and the energy evolution of gas dynamic disaster is seen as the main research line. Based on theoretical analysis, laboratory test, numerical simulation and field investigation, gas sorption-induced strength reduction mechanism, meso-damage and permeability evolution laws of gassy coal under impact effect are researched, and the constitutive equation and coupling model on stress-damage-seepage of gassy coal with original moisture are established. Based on these results above, the synthesis energy criterion on outburst dynamic disaster induced by the instability of thick-hard rock strata could be established, and conditions and models of the disaster could be determined, which could reveal the mechanism of the outburst dynamic disaster. The above research results could be used to achieve multi-scale damage prediction of coal in multiple physical fields and provide theoretical basis for hazard prediction work.

我国50%以上矿区的煤系地层中赋存厚层坚硬顶板岩层，其受大面积采掘作业扰动会发生失稳破断，并形成冲击效应直接作用于下伏高瓦斯煤体，导致其煤与瓦斯突出危险性大大增加。针对不同煤阶煤层原煤自然水分差异大的特点，项目以3种不同煤阶含自然水分煤为研究对象，将顶板厚硬岩层失稳破断的冲击效应作为外部条件，以瓦斯突出动力灾害能量演化为主线，采用理论分析、实验室试验、数值模拟和现场试验相结合的方法，研究含瓦斯煤强度动态变化微观力学机制和冲击效应下含瓦斯煤细观损伤与渗透性演化规律，建立冲击扰动含瓦斯煤损伤本构方程和多相耦合条件应力-损伤-渗流耦合模型；在此基础上，建立冲击扰动含瓦斯煤突出动力灾害的综合能量判别准则，确定突出动力灾害的发生条件和灾变模式，揭示厚硬岩层破断冲击扰动含瓦斯煤突出动力灾变机制。上述研究成果可以实现多物理场和多尺度的煤体损伤破坏预测，为指导煤层突出动力灾害预测工作提供理论基础。

项目以不同煤阶含自然水分煤为研究对象，以顶板厚硬岩层失稳破断的冲击效应为外部条件，以瓦斯突出动力灾害能量演化为主线，采用理论分析、实验室试验、数值模拟和现场试验相结合的方法，研究含瓦斯煤强度动态变化微观力学机制和冲击效应下含瓦斯煤细观损伤与渗透性演化规律，确定突出动力灾害的发生条件和灾变模式，揭示了厚硬岩层破断冲击扰动含瓦斯煤突出动力灾变机制，上述研究成果可为指导煤层突出动力灾害防治工作提供理论基础。主要内容如下：.1）构建了厚硬顶板岩层结构见方失稳模型，并通过地表沉陷观测数据和FLAC3D数值模拟验证了其准确性与可靠性；从应力和能量角度研究了坚硬顶板岩层结构失稳后对下伏煤体的冲击力能效应。.2）对不同变质程度煤孔隙结构特征进行了定性和定量分析。基于光电辐射技术手段，通过最大球算法理论和三维重构建立拓扑性质等价性的孔隙网络模型，对原生煤和构造煤的孔隙网络模型孔腔和喉道参数进行结构表征及精细化识别，分析了变质作用和构造作用对原生煤和构造煤多尺度形态结构的影响。.3）设计、应用了气态吸附法制备不同含水率煤样，对不同变质程度自然水分原煤样和干燥原煤样的吸附解吸特性进行了测定，得到了吸附变形微观损伤演化机制；利用含声发射监测系统的煤岩吸附-渗透-力学耦合特性测定仪测定了多重因素作用下含瓦斯煤的损伤-渗透特性，获得了与冲击效应相符的力学路径下的含瓦斯煤细观损伤、渗透特性及其耦合机制。.4）构建煤岩-瓦斯多场耦合模型，利用COMSOL数值模拟获得了不同应力条件下含瓦斯煤体的自身致灾潜能，获得了岩床失稳诱发煤岩动力灾害的综合能量判别准则；进行了不同含水率条件下真三轴煤与瓦斯突出试验，研究了水分抑制解吸对突出的影响，得到不同含水率煤体发生突出的灾变条件和灾变模式。.5）综合上述研究，系统获得了厚硬岩层结构失稳冲击扰动含瓦斯煤动力灾变机制和下伏离层瓦斯灾变机制，提出了厚硬岩层下伏煤岩瓦斯动力灾变能量判据和综合防治方法，并在杨柳煤矿等工程现场进行了成功应用。