Effect of Sealing on Train Fires in a Heavy-Haul Railway Tunnel

Tunnels have been increasingly built at airports to improve the transportation network. A fire in the railway tunnel would seriously threaten airport safety. For heavy-haul railway tunnel fires, an effective sealing strategy can help control the fire and smoke development. This paper presents a numerical study on the effects of sealing ratio and sealing time on train fire behaviors in a heavy-haul railway tunnel. Three sealing ratios of 50–100% and five sealing times of 200–1000 s were investigated. The heat release rate (HRR), smoke temperature, and CO concentration were analyzed. The results showed that when the sealing ratio increases and the sealing time decreases, the HRR gradually decays, and it drops to zero within 100 s after full sealing due to the fire self-extinction. The incomplete sealing decreases the ceiling temperature in the fire development stage but increases the ceiling temperature in the steady burning stage. The complete sealing in both early and late burning stages decreases the ceiling temperature. Because the burning train acts as an obstacle, the temperature and CO concentration vary between the two tunnel ends. The effective unsealing strategy for heavy-haul railway tunnel fires is therefore proposed.