Study on the motion fire of one-train and multiple-train in the tunnel

Tunnel fire often causes serious consequences because of the large length-width ratio of tunnels. Existing research mainly focused on the stationary fire, but motion fire is more complicated and the movement of other trains has great influence on the fired train when there are more than one train running in the tunnel simultaneously. This study investigates the characteristics of motion fire in one-train and multiple-train tunnels. First, the theoretical models of one-train and multiple-train tunnels with longitudinal ventilation are established. The critical speed model is established and applied to one-train tunnel and multiple-train tunnel scenarios. Experiments are carried out to study the motion fire and the accuracy of theoretical models are validated. Then, the critical speed and pressure of one-train and multiple-train in the tunnel are investigated. The variation trends of critical speed and pressure under different fire source intensity, train speed, and train deceleration are obtained. Finally, the method is developed to obtain the minimum train speed of a fired train in the tunnel. The relationship between the fire source intensity and minimum train speed is analyzed. This study provides a guideline and reference for the control of motion fire in the tunnel. •Theoretical models of one-train and multiple-train tunnels are established.•Critical speed model is built and applied to the different tunnel fire situations.•Critical pressure increases with the rise of three influencing factors.•Critical speed increases with the rise of fire intensity and train deceleration.•The minimum train speed of a fired train running in the tunnel is proposed.