Influence Laws of Train Operation Parameters and Bypass Tunnel Parameters on Bypass Tunnel Ventilation Effect in Subway Station Track Zone

［Objective］ Due to space constraints, some subway station piston ventilation shafts are set up in the station track zones, and a bypass tunnel is used for connecting the ventilation shaft to the main line tunnel outside the track zone. It is necessary to study the influence laws of train operation parameters and bypass tunnel parameters on the ventilation effect of the bypass tunnel. ［Method］ A one-dimensional tunnel ventilation network model of a certain line with bypass tunnel is established, and the ventilation effect of the bypass tunnel under different train pair numbers, train velocities and bypass tunnel lengths is simulated and analyzed. ［Result & Conclusion］ When there is a bypass tunnel, the increase in train pair numbers and train speed can both effectively improve the tunnel piston air volume. When the bypass tunnel is located at the train entrance end, the maximum change value of the tunnel piston air volume increases by 5.2 m3/s and 5.1 m3/s respectively with the increase of train pair numbers and train speed. When the bypass tunnel is located at the exit end, the maximum change value of the tunnel piston air volume increases with train pair numbers and train speed by 11.8 m3/s and 16.7 m3/s respectively, indicating that tunnel piston air volume is more affected in the latter case. When the bypass tunnel is located at the exit end, the tunnel air temperature drops more significantly, and the maximum temperature drop of the tunnel air increases by 1.6 ℃ and 3.5 ℃, respectively, with the increase in train pair numbers and train speed. Changes in bypass tunnel lengths have little effect on the changes in tunnel air volume and air temperature, and the tunnel thermal environment reaches best with a bypass tunnel length of 18 m.