The Research On Water Infusion Parameters And Construction Technology For Longwall Top Coal Caving Face Used For Tang'an No.3 Coal

Water infusion is not only widely used for guarding against mine disaster such as coal dust blast, pressure bump, gas and coal outburst, but also used for softening top coal, and improving the caving ability of top coal. But Chinese coal embedding condition is multiform, this method does not always receive ideal effect.The thesis takes LanHua Tang'An No.3 coal seam for example. Firstly, the basic physic and mechanical property, reflectance of vitrinite, and the maceral are determined, then wetting property, crack property, pore size distributing, water conduction coefficient, and its changing rule are experimentally studied, finally the permeability of No.3 coal seam is comprehensively appraised. After analysis, 4 main appraising indexes of permeability of water infusion are chosen. They are water conduction coefficient, porosity ratio, cranny fractal dimension, the quantity of cranny. Based on numbers of experimental datum, the appraising indexes of permeability of No.3 coal is determined with fuzzy mathematical theory, and with the permeability appraising method, the permeability appraising index of No.3 coal is concluded as 59.63, which belongs to the first grade ofâ…¢ class coal which is classification as the medium coal seam from the permeability view. So in the process of water infusion, only if you choose the proper area for infusion, ensure the infusion time the infusion effect will be won with no wetting agent. According to the appraising result, long drilled hole with moving pressure is advised for water pre-infusion, and the final infusion should be within 5MPa, while the distance between the holes should be 15m.After studying the dust particle size distribution rates of the sample caused different impacting method (with different hammer dropping height and impacting frequency), and by different soaking time with normal pressure and the moisture content, the dust particle size distribution rule of No.3 coal is got, and it is furtherly concluded that infusing water into coal seam can efficiently reduce the dust produced by cutting coal, blast, and drilling in the process of producing coal. But in order to increase moisture content of coal and time of water affecting coal, water infusion must be taken 20 days before caving work surface.Finally, based on the above study and other former studies, the basic parameter and technology of infusing water into long-wall top coal caving work surface of No.3 coal seam are designed, the water infusion equipment is chosen, and the specific steps of water infusion and determination are designed for 3410 long-wall top coal caving work surface.