Among the three overburden zones (the caving zone, the fracture zone, and the continuous deformation zone) in longwall coal mining, the continuous deformation zone is often considered to be continuous without cracks, so continuum mechanics can be used to calculate the subsidence of overburden strata. Longwall coal mining, however, will induce the generation of wide cracks in the surface and thus may cause the continuous deformation zone to fracture. In this paper, whether there are cracks in the continuous deformation zone as well as the height of overburden fracture in longwall face and the subsidence and deformation of strata of different fracture penetration ratios were studied by means of physical simulation, theoretical analysis and numerical simulation. The results show that: (1) Rock stratum starts to fracture as long as it has slightly subsided for only tens of millimeters, and the height of fracture development is the height of working face overburden. (2) With the increase of fracture penetration ratio, the subsidence of key strata remains basically unchanged; the surface deformation range and the maximum compression deformation decrease, while the maximum horizontal movement and maximum horizontal tensile deformation increase. Therefore, the subsidence of overburden strata which have fractured but have not broken can be calculated through the continuum mechanics method.

中文翻译：

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基于关键层理论的长壁工作面覆岩裂缝高度。

在长壁采煤的三个覆岩带（崩落带，断裂带和连续变形带）中，连续变形带通常被认为是连续的而没有裂缝，因此可以使用连续力学来计算覆岩的沉降。地层。但是，长壁采煤将引起地表大裂缝的产生，从而可能导致连续变形区破裂。本文通过物理模拟，理论分析和数值模拟，研究了长壁工作面连续变形区中是否存在裂缝以及上覆岩层裂缝的高度以及不同裂缝渗透率的地层沉降和变形。结果表明：（1）岩石地层只要稍微沉降仅几十毫米就开始破裂，裂缝发展的高度就是工作面覆盖层的高度。（2）随着裂缝渗透率的增加，关键层的沉降基本保持不变；表面变形范围和最大压缩变形减小，而最大水平移动和最大水平拉伸变形增加。因此，可以通过连续力学方法来计算已破裂但尚未破裂的上覆岩层的沉降。表面变形范围和最大压缩变形减小，而最大水平移动和最大水平拉伸变形增加。因此，可以通过连续力学方法来计算已破裂但尚未破裂的上覆岩层的沉降。表面变形范围和最大压缩变形减小，而最大水平移动和最大水平拉伸变形增加。因此，可以通过连续力学方法来计算已破裂但尚未破裂的上覆岩层的沉降。