| According to the data and literatures collected from 28 mines in Huainan and Fukang coal-mining areas, geological conditions in the two areas were summarized, such as strata, geological structure, coal-forming environment, hydrogeological characteristics, evolution of tectonic stress field etc. Through field investigation and sample analysis down hole, the characteristics and distribution rules, such as geological structure, thickness of coal seam, metamorphic grade and coal body structure, were found out. Development and filling of joint and exogenous crack were observed and their occurrence and density were measured underground. Types of coal and rock and development of endogenous fracture in samples were observed, and endogenous fracture density was measured. Characteristics, genesis and distributions of exogenous and endogenous fractures of coal reservoir in Fukang mining area were clarified. Through observation statistics of optical microscope, the characteristics, filling and distribution of the microscopic fracture were analyzed. From the mercury injection experiment of coal samples, the characteristics, distribution of pores and their control factors were achieved.he specific surface area and pore volume of micropore, little pore, middle pore and macropore generally decrease in turn in Fukang mining area under the control of the coal rank. The content of pore is most in the west and least in the east. coal seam exogenetic fractures are mainly controlled by the shearing action in Fukang mining area. They mainly develop in the east and west of the mining area. The advantage direction of fissure is NW in southern syncline and SE in northern syncline. Because of the influence of buried depth, endogenous cracks of coal seams in shallow Xishanyao group are more developed than those in deep Badaowan group., the western and eastern micro crack densities are larger than the middle’s. Under the influence of surface and ground water, the western and eastern crack filler is more than the middle’s. |
