针对超大采高工作面易发生煤壁片帮的问题, 以曹家滩煤矿122104超大采高工作面为背景, 综合运用现场监测、数值模拟和理论分析等方法, 研究了不同顶板压力条件下超大采高工作面煤壁塑性区、应力及位移分布特征, 建立了煤壁片帮力学模型, 确定了煤壁挠度最大点位置, 揭示了顶板压力变化对煤壁稳定性作用机理。研究结果表明: 煤壁破坏以拉裂为主, 且多发生在中部或中上部区域, 其形态通常呈现为半月状内凹或台阶状, 煤壁平均片帮深度为0.41 m, 最大片帮深度平均为1.53 m, 片帮层位主要出现在底板上方4.4~8.0 m高度范围内, 煤壁片帮程度与顶板压力成直接相关性, 周期来压期间片帮加剧。初次来压后形成悬臂梁及组合悬臂梁结构, 随着工作面的推进, 顶板垮落和煤壁破坏加重, 超前支承压力峰值及应力集中系数显著上升, 工作面煤壁片帮与矿压显现成正相关关系。数值模拟结果显示, 随着开采深度的增加, 顶板压力增大, 煤壁稳定性降低。不同埋深下的煤壁压力对煤壁挠度表现出非对称特性, 煤壁挠度随埋深的增加而增大, 煤壁最大挠度位置随埋深的增加而沿煤壁逐步上移, 最大变形区域在0.59~0.94倍采高处。

To address the issue of coal wall spalling in ultra-high mining faces, the 122104 ultra-high mining face at Caojiatan Coal Mine was taken as the background, and field monitoring, numerical simulation, and theoretical analysis were used to investigate the distribution characteristics of the plastic zone, stress, and displacement of the coal wall under different roof pressure conditions. A mechanical model of coal wall spalling was established, the location of the maximum deflection point of coal wall was determined, and the mechanism on the stability of coal wall affected by the roof pressure was revealed. The results show that coal wall failure was primarily due to tensile cracking, often occurring in the middle or upper-middle areas, typically manifesting as a crescent-shaped concave or stepped form. The average depth of coal wall spalling was 0.41 m, with an average maximum spalling depth of 1.53 m. The spalling layer mainly occured at a height range of 4.4–8.0 m above the floor. The degree of coal wall spalling was directly correlated with roof pressure, with spalling exacerbated during periodic weighting. After the initial weighting, cantilever and combined cantilever structures were formed. As the mining face advances, roof collapse and coal wall damage intensify, the peak of the advanced abutment pressure and the stress concentration factor increase significantly. The degree of coal wall spalling was positively correlated with the mine pressure. Numerical simulation results show that roof pressure increased and coal wall stability decreased with increasing mining depth. The coal wall pressure under different depths exhibited an asymmetric characteristic with respect to coal wall deflection, which increases with depth. The location of the maximum coal wall deflection moved upward along the coal wall with the increase of depth, and the maximum deformation area occurred at the location of 0.59−0.94 times the mining height.