基于流固耦合的单采与复采工作面覆岩渗透性研究

浅埋煤层单采与复采覆岩渗透性变化与工作面突水关系密切，文章针对隆德煤矿地质条件，应用FLAC3D内嵌的FISH语言模块，依据覆岩体积应变与其渗透系数的关系对软件进行二次开发，对煤层单采与复采工作面覆岩应变场、渗透系数场分布规律进行数值模拟研究。结果表明：工作面覆岩渗透性与其体积应变密切相关；单采1-1煤与复采2-2煤引起的岩层拉伸变形发生在工作面顶部和底部，压缩变形发生在工作面周围的支承压力区和弯曲下沉带，在拉伸、压缩变形区的交界区域易形成剪切破坏；单采1-1煤引起上覆中砂岩和细砂岩不协调变形，离层空间发育，此处渗透性最强；复采下层2-2煤后覆岩渗透系数场形似马鞍形，同时上层1-1煤覆岩的变形破坏进一步加剧，最大渗透系数比值由1-1煤终采时的1.46增至1.91，增幅达$31\%$ 。研究结果可为同类型浅埋煤层单采与复采渗透性研究提供参考，为矿井突水防治提供理论依据。

The change of overburden permeability in single mining and repeated mining of shallow coal seam is closely related to the water inrush of the working face. According to the geological conditions of Longde Coal Mine, using the FISH language module embedded in FLAC3D on the basis of the relationship between volume strain and permeability coefficient, the strain field and permeability coefficient field distribution of overburden in single mining and repeated mining face of coal seam was simulated. The results show that the overburden permeability of the working face is closely related to its volume strain. The tensile deformation caused by single mining of 1-1 coal and repeated mining of 2-2 coal occurs at the top and bottom of the working face, while the compression deformation occurs in a butment pressure area and continuous bending zone around the working face. Shear failure is easy to occur at the junction of two deformation zones. The single mining of 1-1 coal causes uncoordinated deformation of the overlying medium sandstone and fine sandstone, and the development of the bed separation space, where the permeability is the strongest. The repeated mining of 2-2 coal will intensify the overburden deformation and failure of 1-1 coal, and the overburden permeability coefficient field presents a saddle shape, with the maximum permeability coefficient ratio increasing by$31\%$ from 1.46 to 1.91. The research results can serve as a reference for the study of the permeability of similar shallow coal seams in single mining and repeated mining, and provide a theoretical basis for the prevention and control of mine water inrush.