针对松散层第四含水层突水灾害防治问题, 以岩层控制的关键层理论和中厚板理论为基础, 对松散层第四含水层水压与主关键层之间的破断运移规律进行研究。统计并分析了6个典型厚松散层矿区的18个矿井松散层第四含水层水压、松基比及松散层厚度之间的关系, 发现松基比和松散层厚度与松散层第四含水层水压之间呈显著的正相关。通过中厚板理论分析了不同松散层第四含水层水压条件下关键层破断力学机理, 得出随着松散层第四含水层水压的增大, 关键层破断力学因素由拉破断转化为剪破断。数值模拟分析验证了, 随着水压的增加, 剪应力占比逐渐增大, 且关键块之间的结构也由连续且稳定砌体梁结构转换为非连续易失稳的台阶岩梁结构。松散层第四含水层水压的增大可能促使采空区原本稳定的砌体梁结构转化为台阶岩梁结构, 促进导水裂隙带的发育。同时, 在关键层岩块结构中出现了砌体梁与台阶岩梁共存的现象。不同松基比岩移边界线具有明显的“类指数曲线”特征, 随着松基比的增加, 岩移边界线由“直线”转化为“类指数曲线”, 且工作面推进过程中的覆岩运移具有明显的分区特征。

For the prevention and control of water inrush disasters in coal mining under loose and pressurized aquifers, our study delves into the fracturing dynamics between water pressure in the fourth aquifer of the loose layer and the movement of the main key strata. Based on on the key strata theory and the medium thick plate theory, we analyze the statistical relationship among water pressure, loose base ratio and loose layer thickness in the fourth aquifer of 18 mines in 6 typical thick loose layer mining areas. Our findings reveal a significant positive correlation between loose base ratio, loose layer thickness and water pressure in the fourth aquifer of the loose layer. Using the medium-thick plate theory, our analysis demonstrates a notable transition of fracture mechanics mechanism of the key strata from tensile to shear fracturing with the increase of water pressure in the fourth aquifer of different loose layers. Numerical simulation analysis validates this fracturing shift of the key strata from tensile to shear fracture. As water pressure increases, the proportion of shear stress increases gradually, causing the structure transition between key blocks from a continuous and stable masonry beam structure to a discontinuous and easily unstable stepped rock beam structure. Furthermore, the increased water pressure in the fourth aquifer of the loose layer may accelerate the transformation of the originally stable masonry beam structure in the goaf into a stepped rock beam structure, thereby promoting the development of water conducting fracture zones. Consequently, the key strata rock block structure exhibits the coexistence of masonry beams and stepped rock beams. The boundary lines of rock movement with different pine base ratios show obvious "exponential curves" characteristics. As the pine base ratio increases, the boundary lines of rock movement shift from "straight lines" to "exponential curves", and the displacement during the advancing process of the working face displays clear zoning characteristics.