深部开采煤体变形破裂与瓦斯解吸渗流耦合机理研究

In simultaneous extraction of coal and methane, the coupling law of mining coal deformation and break and methane desorption and seepage is one of the key scientific problems. But at present, few studies dedicate to the coupling mechanism under the effect of multiple factors, especially the effect of high temperature and high stress is more obvious and complex in deep mining.In view of this problem, the project intends to apply electron microscope scanning, nitrogen adsorption experiment, mercury injection experiment, etc., combining with the fractal theory, the structure type and characteristic rules of coal pore microstructure of typical deep mine are researched. Using high pressure absorption-desorption experiment device, the gas adsorption and desorption rules and characteristics of the coal under high temperature and high pressure are researched. Through the self-developed coal deformation and break and gas desorption and seepage experiment system, the rules of coal deformation and break and gas desorption and seepage under high temperature and high stress are researched, and the whole process of evolution characteristics of dynamic coupling is obtained. Using rock mechanics, mass transfer theory, seepage mechanics, and fluid dynamics theory, the coupling model of coal deformation and break and gas desorption and seepage considering the strain of gas adsorption and desorption and change of effective stress is established, and it will reveal interaction mechanism. Under coupling effects of mining coal deformation and break and methane desorption and seepage, the laws of coal-bed methane migration and drainage are studied by numerical simulation and field tests. It has important theoretical and practical value for improving and developing the theory and technology system of safety simultaneous extraction of coal and coalbed methane in deep mining.

采动煤体变形破裂与瓦斯解吸渗流耦合规律是煤与瓦斯共采中的关键科学问题之一，但目前两者耦合机制在多因素影响下的研究不多，尤其是深部开采高温高应力等因素对其作用效应更加复杂。针对该问题，项目拟应用电镜扫描、氮吸附实验、压汞实验等，结合分形理论，研究典型深部矿井煤样孔隙微结构类型及特征规律。采用高压吸附解吸实验装置，研究高温高压下煤对气体的解吸规律与特性。通过研发煤体变形破裂与瓦斯解吸渗流实验系统，研究高温高应力下煤体变形破裂与瓦斯解吸渗流规律，得到两者全过程动态耦合演化特征。利用岩石力学、传质学、渗流力学及流体动力学等理论，构建考虑瓦斯解吸应变及有效应力变化影响的煤体变形破裂与瓦斯解吸渗流耦合模型，以揭示两者相互作用机制。运用数值模拟及现场试验，研究采动煤体变形破裂与瓦斯解吸渗流耦合作用下的煤层瓦斯运移及抽采规律。这对于完善深部煤与瓦斯共采理论与技术体系具有重要的理论和实践价值。

随着煤矿开采深度增加，煤层瓦斯含量逐渐增大，抽采是解决瓦斯问题的根本性措施，煤层钻孔抽采是主要方法之一，其布置参数与煤层瓦斯解吸、煤体渗透等特性密切相关，应着力于研究煤体变形破裂与瓦斯解吸渗流规律，从而实现高效抽采与控制瓦斯。项目综合应用理论分析、数值模拟、实验室实验、现场工业性试验等相结合研究方法开展研究。.通过低温氮吸附法和压汞法测试了煤样孔隙参数，确定了煤的孔隙全孔径段联孔位置，提出了联孔方法，得到煤样全孔径段孔隙结构特征，优选出全孔径段综合分形模型，揭示了分形维数与煤质参数、孔隙参数及显微组分的关系。开展了不同温度、粒度、水分等影响下煤样瓦斯解吸放散实验，得到不同温度和不同解吸平衡压力条件下，煤样对甲烷、氮气、二氧化碳以及多组分气体的分压解吸特征，明确了多组分气体分压解吸过程各气体浓度变化规律，得到了温度、粒度、水分等影响下煤样瓦斯解吸放散规律，建立了煤体瓦斯解吸放散多因素综合控制模型。研发出煤体变形破裂与瓦斯解吸渗流耦合实验系统，得到不同温度条件下，甲烷、氮气、二氧化碳等气体吸附、解吸、渗流与煤体变形之间相互作用规律，以及不同轴压与围压比条件下，甲烷、氮气、二氧化碳渗流与煤体变形耦合特征。通过煤层瓦斯渗流方程、煤层变形方程及Langmuir单分子层吸附解吸方程，结合含瓦斯煤岩体渗透率动态方程，构建出考虑煤体变形与瓦斯解吸耦合的瓦斯抽采渗流模型，揭示出两者相互作用机制。获得了不同吸附解吸效应下煤层渗透率和瓦斯压力变化规律，定量化表征了煤层瓦斯抽采布置参数，并进行现场工业性试验，在保证抽采达标的前提下，取得了良好的工程效果。项目研究对于深化适合于深部开采条件的煤体瓦斯吸附、解吸、渗流理论，完善煤与瓦斯共采理论体系，以及提高瓦斯灾害防治水平等具有一定的科学价值。