A Study on the Influence of Rail Top Smoke Exhaust and Tunnel Smoke Exhaust on Subway Fire Smoke Control

The special emergency plan for subway fires in China stipulates that when a fire occurs at a train stop, it is necessary to confirm whether the fire mode of the tunnel ventilation system is implemented. Because of the setting mode of tunnel ventilation and smoke exhaust in the station track area, the smoke exhaust at the rail top and tunnel cannot operate at the same time. To study the influence of rail top smoke exhaust and tunnel smoke exhaust on subway fire smoke control when a train stops at a station, we take an island station as an example. A 1:1 full-scale numerical model is established to study the smoke spread area, temperature field distribution, and carbon monoxide concentration. The results show that when a train fire occurs in a subway station, the rail top smoke exhaust mode has the best smoke exhaust effect compared with the other three smoke exhaust modes. In this mode, the smoke diffusion in the carriage is the slowest and the available escape time of personnel is the longest. Therefore, it is recommended to adopt the rail top smoke exhaust mode in case of train fire in the subway station; that is, open the smoke exhaust outlet on the rail top for smoke exhaust, and organize personnel to evacuate to the safe position of the platform through the connecting channel and escape exit. If conditions permit, local small fans can also be added to meet the requirements of smoke exhaust. The research results can provide guidance for the emergency plan and provide strong support for promoting the improvement of the fire emergency plan.