Effect of Construction Ventilation Scheme on Pollutant Transport in a High-Speed Railway Tunnel

Abstract

To find out the distribution of dust and harmful gases and check the effect of ventilation and dust prevention after blasting in tunnel construction with the drilling and blasting method, the wind velocity, dust concentration and the concentration of harmful gas in You-zhu-shan tunnel of Gui-Guang high-speed railway were studied by CFD simulation and field test. The ventilation scheme optimization was carried out and the optimum scheme of main tunnel as air intake while parallel heading as air outlet is put forward. The results showed that the concentration of CO in the tunnel working area is reduced to 24ppm after ventilation 24minutes. Dust concentration maximum lies in the working tunneling side which involves no direct air flow from air duct. And it will be reduced by the continuous dust discharging, trapping and settling along the tunnel due to turbulent diffusion and entrainment of jets. The dust concentration is of a large variation range between trolley and the tunnel portal. It is in high number in tunnel face due to the influence of trolley through the accumulation of the dust around, which will result in a poor working environment.