Study On Ventilation Optimization And Gas Control Measures For Highway Tunnel Construction

With the development of economy,China’s tunnel construction has entered an era of rapid development.However,safety accidents often occur in the process of tunnel construction,especially in accidents and disasters.Therefore,many domestic scholars have carried out a lot of research and achieved fruitful results.In addition,the coal seam strata in southwest China,especially in Yunnan and Guizhou,are very developed,and the probability of tunnel construction through coal seam increases.Because the construction equipment and facilities of the current tunnel construction enterprises do not have explosion-proof function,and the exploration and research of coal seam gas disaster prevention measures are still in the stage of experience and exploration,According to the engineering background of Yangbaozhai Gas Tunnel,the gas source,ventilation scheme and ventilation optimization are explored by means of data reference,theoretical analysis,experimental research and numerical simulation.The main findings are as follows:(1)Based on the determination of the gas adsorption constant,gas dispersion index,robustness coefficient f value,coal seam gas pressure and coal seam gas content.(2)The ventilation scheme of Yangbaozhai tunnel is designed,including the calculation of the required air volume,the selection of the jet fan and the axial flow fan,and the required air volume during tunnel construction.(3)Based on the Fluent numerical simulation software,the optimization study is carried out by comparing and analyzing the different height of jet fan arrangement,the different distance between jet fan and palm face and the distance between air pipe and palm face.(4)The construction process of uncovering coal and preventing outburst is summarized,and the construction requirements are pointed out,and the advanced geological drilling of Yangbaozhai tunnel and the measures of gas drainage by borehole are introduced.Taking Yangbaozhai Tunnel as the engineering background,the gas monitoring scheme of Yangbaozhai Tunnel is introduced,and the gas concentration at the top of the tunnel,at the entrance of the tunnel and at the second liner car is monitored for a period of time.