在国家自然科学基金重点项目《厚煤层全高开采方法基础研究》资助下,通过对综放开采工作面前方顶煤裂隙的现场观测和实验室顶煤裂隙的细观研究,分析了顶煤裂隙分布的宏、细观特征;运用多重分形理论讨论了顶煤裂隙结构的不均匀性和各向异性;基于现场工作面前方顶煤节理裂隙分布,运用UDEC软件,对同一煤层地质条件下不同厚度的综放开采与分层开采采场进行数值计算;分析了应力变化对裂隙岩体渗流的影响,得出了裂隙岩体的渗透系数与应力的关系表达式,结合综放开采的实际,给出了综放开采工作面前方顶煤渗透系数的数学表达式。主要研究结论为: (1)煤层裂隙的形成不仅受地质因素的影响,而且受采掘等工程因素的影响,因此,在定量研究煤层裂隙渗透性时必须考虑工程因素对裂隙发育程度的影响。裂隙分布表明:顶煤裂隙的分布既有一定的随机性,又有一定的规律性。 (2)简单分形和多重分形研究顶煤裂隙,研究表明:当各方向的D_0值变化越大,则表明顶煤裂隙发育的各向异性就越明显,且某一方向多重分维值C_h越小,则该方向裂隙结构就越复杂,分布也越不均匀;相反,多重分维值C_h值越大,则该方向裂隙体结构就相对均匀。因此,用各向分维值D_0和裂隙不均匀系数C_h可以分别定量表示顶煤裂隙的各向异性和不均匀性。 (3)综放开采的卸压 Supported by the National Natural Science Foundation of China, “Basic Research on Full-Height Mining Method of Thick Coal Seams”, through the field observation of top coal fractures in front of fully mechanized caving mining work and the mesoscopic study of top coal fractures in laboratory, the distribution of top coal fractures Based on multi-fractal theory, the inhomogeneity and anisotropy of top coal fracture structure are discussed. Based on the distribution of top coal joint fissures in front of working face, UDEC software is used to study the influence of different thickness Fully mechanized caving mining and stratified mining stope, the influence of stress changes on seepage of fractured rock mass is analyzed, and the expression of relationship between permeability coefficient and stress of fractured rock mass is obtained. Combined with the practice of fully mechanized top coal caving mining, A mathematical expression of permeability coefficient of top coal in front of fully mechanized top coal caving mining. The main conclusions are as follows: (1) The formation of coal seam fissures is not only affected by geological factors, but also influenced by excavation and other engineering factors. Therefore, the influence of engineering factors on the degree of fissure development must be considered when quantitatively studying the fissure permeability of coal seam. The distribution of fractures shows that the distribution of top coal fractures has both a certain degree of randomness and a certain degree of regularity. (2) Simple fractal and multifractal study of top coal fissure, the study shows that: when the D_0 value changes in all directions, the more obvious the anisotropy of top coal fracture development, and the multi-fractal dimension C_h in one direction The more complicated the fracture structure in the direction is, the more uneven the distribution is. On the contrary, the larger the multi-fractal dimension C_h is, the fissure structure in the direction is relatively uniform. Therefore, the anisotropy and inhomogeneity of the top coal fractures can be quantitatively expressed by using the fractal dimension value D_0 and the non-uniform fracture coefficient C_h respectively. (3) Pressure relief in fully mechanized caving