Study on Environmental Testing and Ventilation Design Parameters of Extra-Long Tunnel

In order to explore the optimization of air environment and ventilation design parameters in China's extra-long tunnels, this study first analyzed the statistical data of pollutant emission from motor vehicles in China, combined with literature research, and found that the concentration of NO_x in China's tunnels was relatively high, and gradually became the most concerned pollutants in tunnel ventilation. In this study, a field study was carried out in the Yanglin extra-long tunnel in Yunnan. The results show that the peak NO₂ concentration exceeds the ventilation design limit by 2.1 times during the test period, and the emission factors of CO, NO₂ and PM of gasoline vehicles are 0.79 g/(km·veh), 0.04 g/(km·veh) and 10.0 mg/(km·veh), respectively. diesel vehicles are 2.18 g/(km·veh), 1.27 g/(km·veh) and 149 mg/(km·veh), respectively. Compared with the pollutant emission values of domestic and foreign tunnel ventilation design standards, it is found that the current standard values in China are too large. According to the measured emission factors, the required air volume is calculated, and the result is more than 50% lower than the required air volume in Guidelines for Design of Ventilation of Highway Tunnel, which is similar to the required air volume in Standard for the Design of Road Tunnels, and the control item of the required air volume is NO₂ concentration. The results of this study can provide reference for the calculation of pollutant emission and air demand in tunnel ventilation design in China.