掌握特厚煤层开采覆岩运移及采动裂隙时空演化特征是分析特厚煤层开采对上覆含水层影响及保障矿井安全生产的重要前提。以建庄煤矿4-2特厚煤层实际开采地质条件为背景，在构建物理相似模型的基础上，分析特厚煤层开采覆岩垮落及位移变化特征，提出覆岩裂隙密度定量分析方法，研究特厚煤层开采覆岩裂隙时空演化特征。结果表明：特厚煤层开采条件下，覆岩周期来压步距相对较小，最大裂采比可达30以上，此时传统导水裂隙带高度计算公式并不完全适用，且其计算结果普遍偏小；覆岩垂直位移云图能较好地反映覆岩垮落破断及裂隙分布特征。当覆岩导水裂隙带高度未发育至最大值时，覆岩垂直位移呈现外侧“梯形”-内侧“拱形”分布；覆岩裂隙密度变化能够直观反映其裂隙时空演化情况。不同推进距离覆岩高裂隙密度分布区域基本呈“梯形”分布，顶板初次破断时覆岩裂隙密度达到峰值，随推进距离的增大，覆岩最大裂隙密度呈指数函数递减。当工作面回采结束后，高裂隙密度主要分布于开切眼与停采线上方，形成侧向裂隙分布区；采空区中部覆岩裂隙密度整体较低，反映该区域覆岩压实闭合作用良好。

The movement of overburden and the spatial-temporal evolution characteristics of mining-induced fractures in extra-thick coal seams are considered essential prerequisites for analyzing the impact of mining on overlying aquifers and ensuring the safe operation of mines. The analysis of overburden collapse and displacement characteristics during mining in the 4-2 extra-thick coal seam at Jianzhuang coal mine was conducted through the construction of a physical similarity model based on actual geological conditions. A method for the quantitative analysis of overburden fracture density was proposed, and the spatial-temporal evolution characteristics of mining-induced fractures in extra-thick coal seams were investigated. The results show that under extra-thick coal seam mining conditions, the overburden periodic compression step distance is observed to be relatively small, and the maximum fracture-to-mining ratio is determined to exceed 30. Under these circumstances, traditional formulas for calculating the height of the water-conducting fracture zone are considered not entirely applicable, and the height is generally underestimated by the calculation results. The collapse and fracture distribution features are effectively reflected by the vertical displacement contour maps of the overburden. A "trapezoidal" distribution is observed on the outer side of the overburden displacement in the water-conducting fracture zone, while an "arch" distribution is exhibited on the inner side. The spatial-temporal evolution of fractures is intuitively reflected by changes in overburden fracture density. The high fracture density zone in the overlying strata is generally distributed in a trapezoidal shape with different advancing distances. The peak fracture density is reached during the initial rupture of the roof. The maximum fracture density in the overlying strata decreases exponentially as the advancing distance increases. High fracture density is mainly distributed above the open-off cut and the stopping line after the working face is finished. Lateral fracture zones are formed in these areas. A lower fracture density is generally observed in the overlying strata of the goaf center. This reflects that effective compaction and closure of the overlying strata is achieved in this region.