The huge, inclined goaf formed by the mining of steeply inclined and extra thick coal seams has the characteristics of occupying a large space and being subject to complex breaking behavior of its overlying rock structure, especially the rock block structure characteristics of the interface area between the goaf and the lower working face which is difficult to be characterized, leading to a hidden danger when mining the lower working face. In response to the aforementioned problems, the following conclusions are drawing as follows: (1) with the aid of the contradiction method, the critical condition governing instability of the triangular articulated structure was obtained to explain the correctness of the assumption of the triangular hinged structure; (2) three-point truss structure was composed of key layer blocks; (3) in the stabilization stage of the triangular hinged structure, the fracture network area was extracted, and the centerline intensive equivalent method of a single fracture segment was adopted to directly measure the equivalent length. Meanwhile, the value of equivalent average width with the equivalent length of a single crack was calculated by integral operation and equivalent figure calculation; (4) the mathematical expressions of permeability which was positively exponential function related to the ratio of equivalent average width to equivalent length were derived. Furthermore, the vectorized solution of seepage rate was carried out respectively for the goaf area and the extracted network area by using COMSOL software. The distribution of the strong seepage area of CBM and the ratio of equivalent average width to equivalent length is found to be consistent to a large extent, which provides theoretical support for subsequent CBM management.

陡斜特厚煤层开采形成的巨大倾斜采空区具有占地大、上覆岩石结构破碎行为复杂的特点，特别是煤层间界面区的岩块结构特征。采空区和下工作面难以表征，导致下工作面开采存在隐患。针对上述问题，得出如下结论：（1）借助矛盾法，得到了控制三角形铰接结构失稳的临界条件，说明了三角形铰接结构假设的正确性。 ; (2)三点桁架结构由关键层块组成；(3)在三角铰结构稳定阶段，提取缝网面积，采用单缝段中心线密集等效法直接测量等效长度。同时，通过积分运算和等效图形计算计算出等效平均宽度与单个裂纹等效长度的值；(4)导出了渗透率的数学表达式，渗透率与等效平均宽度与等效长度之比呈正指数函数关系。此外，利用COMSOL软件分别对采空区和抽出的管网区进行了渗流率的矢量化求解。