Gas Fast Drainage And Uncovering Coal Process Optimization Design And Practice For Tianping Tunnel

Tianping tunnel is the part of Chongqing to Guizhou railway and located in Tongzi County, Guizhou Province, the tunnel need to through 22 layers of coal, but the most layers is thin coal seam or coal line, of which 3 coal seam of tunnel construction has a greater threat, main coal seam belongs to the Longtan coal bearing strata, coal seam gas pressure is higher, also strata containing a lot of fissure water, geological complex, the conventional gas drainage measures not only affect the construction period, and hard to achieve safety uncovering coal requirements. Therefore, by Tianping tunnel gas drainage technology and rapid uncovering technology optimization of coal has important engineering significance and safety.In this paper, making the program of predict the risk of coal and gas outburst for Tianping tunnel, determinate respectively on Tianping tunnel uncovering coal area C6, C5, C3 coal seam of coal and gas and other related parameters. Determine the degree of fragmentation of the coal seam, the consistency coefficient, gas adsorption constant, coal seam gas pressure, gas content and other related parameters. And the final judgment Tianping tunnel coal area is outburst danger zone area. Drainage numerical simulation to determine the radius of 2m gas discharge for Tianping tunnel coal uncovering area, and hole space is 4m. Through the FLUENT software analysis of the borehole gas drainage pressure of gas drainage volume and pumping rate, draw the gas suction pressure of the gas drainage volume is greater drainage rate higher, but size of negative pressure of gas pumping put the radius of influence is not obvious. Through the gas drainage borehole sealing structure design and optimize, improved the tunnel gas drainage borehole to hole sealing and sealing hole efficiency. Using dense boreholes, three layers of coal with gas drainage, leading from the tunnel flat hole play drainage boreholes is gas hole and other methods, in order to solve the current commonly used tunnel gas drainage technology, which greatly improve the gas drainage efficiency, reducing the cost of tunnel construction.Considering the whole guide with Tianping the actual tunnel construction, technical reference method is more mature coal mine uncovering coal technology, and the optimized from ensure tunnel uncovering coal safety of present day Ping tunnel adit area priority ahead of uncovering coal technology ideas, and to guide and hole coal uncovering, design the Tianping tunnel uncovering coal process optimization scheme, to improve the gas drainage efficiency, so that the Tianping tunnel gas drainage and uncovering coal in the overall project than expected ahead of schedule 50 days to complete and realize the Tianping tunnel gas rapid drainage and full uncovering coal for other similar project provides theory and practice reference.