Underground mining engineering causes complex changes in the three-dimensional stress near the working face of a mine, resulting in deformation and failure of the roof and floor rocks, as well as ground subsidence. To study the stress, deformation, and fracture field characteristics of the roof and floor strata due to mining, an indoor large-scale three-dimensional physical similarity model was developed. A novel method was used to simulate the mining process of coal seams. The results show that coal seam mining disrupted the original stress balance; consequently, a bearing pressure was generated in front of the working face, and a significant pressure relief state appeared in a particular area. The collapsed rock blocks of the overburden strata filled the goaf and played a supporting role, causing the overburden stress to increases again to a value close to the original rock stress. After complete mining, the overburden strata subsided, and the floor strata bulged. With an increasing vertical distance from the working face, the deformation of the rock formation gradually decreased. Evident fractured fields were formed in the surrounding rock of the goaf. In the horizontal section of the overburden rock layer, the cracks were distributed in a “rounded rectangular” shape. As the distance from the coal seam increased, the “rounded rectangular” boundary became smoother; the coverage area decreased; and the degree of crack opening and development in the plane decreased. The fractal dimensions of fractures with different overburden heights and different strike positions are calculated using the fractal geometry theory. We found that as the distance from the excavation face increased, the fractal dimensions of the fractures gradually became stable. In addition, numerical simulation methods were used to verify the correctness of the physical similarity model experiments. The research results can provide important references for the stability of deep underground projects such as coal mining process, tunnel excavation process, nuclear waste storage and other engineering stability.

地下采矿工程在矿井工作面附近引起三维应力的复杂变化，从而导致顶板和底板岩石的变形和破坏，以及地面沉降。为了研究采矿引起的顶板和底板地层的应力，变形和断裂场特征，建立了室内大型三维物理相似模型。一种新颖的方法被用来模拟煤层的开采过程。结果表明，煤层开采破坏了原有的应力平衡。结果，在工作面的前方产生了支承压力，并且在特定区域中出现了显着的压力释放状态。覆土层的坍塌岩石块填满了采空区，起到了辅助作用，导致覆盖应力再次增加到接近原始岩石应力的值。完全开采后，上覆岩层消退，地层隆起。随着与工作面垂直距离的增加，岩层的变形逐渐减小。在采空区的围岩中形成了明显的裂隙。在覆盖岩层的水平部分，裂缝以“圆角矩形”形状分布。随着距煤层距离的增加，“圆角矩形”边界变得更平滑；覆盖面积减少；裂纹在平面内的扩展和发展程度降低。利用分形几何理论计算了不同上覆高度和不同走向位置的裂缝的分形维数。我们发现，随着距开挖面距离的增加，裂缝的分形维数逐渐稳定。此外，使用数值模拟方法来验证物理相似性模型实验的正确性。研究结果可为深部地下工程的稳定性提供重要的参考，如煤矿开采过程，隧道开挖过程，核废料储存及其他工程稳定性。