【摘要】 针对沟谷地形浅埋煤层开采中覆岩裂缝发育不稳定、突水溃沙灾害区域难以判定的技术难题，以龙华煤矿20202工作面为研究对象，采用无人机航测获取研究区地形特征，建立物理相似模型，与PFC^2D数值模型进行对比分析。通过网格统计法系统研究了平缓与沟谷地形条件下覆岩裂缝的频数、产状及开度分布特征，结合数值模拟得到孔隙率演化、裂缝总数及地裂缝发育时序等参数，阐明了沟谷区覆岩裂缝动态扩展规律，确定了突水溃沙高风险区域。研究成果揭示了沟谷地形浅埋煤层开采覆岩裂缝发育机制，其结论与现场实测数据具有良好的一致性。研究结果表明：平缓地形覆岩以离层裂缝为主导，而沟谷地形促使覆岩裂缝显著发育，其中沟谷下坡段与沟底区域地表裂缝最为密集；沟谷坡段空间位置显著影响覆岩裂缝发育，沟谷地形下复合基本顶永久性裂缝数量最多，主关键层裂缝发育受地形影响最为显著，数值模型裂缝总数呈现典型的“三段两区”分布特征；沟谷地形覆岩强裂缝带呈非均匀分布，沟谷下坡段与沟底下方区域形成主关键层裂缝密集区。该研究成果为同类条件下工作面突水溃沙灾害易发区的判定提供了科学依据。更多还原

【Abstract】 This study aims to address the problem of unstable distribution of overlying strata fractures in shallow buried coal seam mining in gully terrain and the difficulty of determining the disaster area caused by water-sand inrush at the working face. To this end, with the 20202 working face of Longhua Coal Mine taken as the geological prototype, a physical similarity model and a PFC^2D numerical model were established by observing the topographic characteristics of the study area through UAV photogrammetry. Besides, the frequency, angle, and aperture distributions of overlying strata fractures in the physical similarity simulation results under gentle terrain and gully terrain conditions were investigated through the grid division statistics method. Based on parameters obtained from numerical simulation, such as the porosity variation of the key strata, the total number of model fractures, and the generation time sequence of surface fractures, the dynamic evolution characteristics of overlying strata fractures in gully terrain were clarified, and the target areas prone to water-sand inrush were obtained. The research results, which reveal the law of overlying strata fracture development in shallow buried coal seam mining in gully terrain, basically align with the field measurement results of surface fractures. The main research findings are introduced as follows: The overlying strata fractures in gentle terrain are dominated by bedding separation fractures, while the overlying strata fractures in gully terrain are more developed. Specifically, surface fractures are most densely developed in the downslope section and bottom area of the gully. The spatial location along gully slopes strongly affects the development of overlying strata fractures. The compound main roof in gully terrain shows the greatest number of permanent fractures, and the fracture developmentin the primary key stratum is most sensitive to topography. The total number of fractures in the numerical model displays a typical distribution pattern of “three sections and two zones”. The strong fracture band of the overlying strata in gully terrain is non-uniformly distributed, where dense fracture zones of the key stratum are formed beneath the downslope section and bottom area of the gully. The research findings can provide a reference for the determination of the disaster susceptible area caused by water-sand inrush in the working face under similar conditions.更多还原