Influence of the door opening on the pressure transient caused by the high-speed subway train passing through the double-track tunnel with the mid-partition wall

Double track tunnel with mid-partition wall is a widely used subway tunnel. In such tunnels, in order to avoid the fire door on the middle partition wall from invading the gauge, the fire door is often removed to form door openings. The existence of door opening connects two parallel tunnels, which affects the aerodynamic effect caused by high-speed subway train passing through the tunnel. In this study, a double track tunnel with midpartition wall was taken as an example to analyze the aerodynamic effect of high-speed subway train under the door opening conditions, moreover, the surface pressure of two adjacent tunnels and train surface pressure was also analyzed. In addition, the propagation mechanism of pressure wave in open door tunnel was analyzed in detail, and the superposition law of branch pressure wave caused by open door was pointed out. The results indicated that the presence of door openings is beneficial for controlling the peak pressure on the tunnel surface and train surface. For a door opening with a cross-sectional area of 5 m2 (cross-sectional area ratio of 0.116), when the door opening is located 300 m and 700 m away from the tunnel entrance, the peak positive pressure can be reduced by up to 21.9 % and the peak negative pressure can be reduced by 21.1 %. The cross-sectional area and number of door openings have a limited effect on reducing the peak pressure of the tunnel. Compared to the number of door openings, the position of the door opening has a more significant impact on the peak pressure inside the tunnel and on the surface of the train.