Abstract:  In order to explore the smoke diffusion characteristics of fire train when braking to the underground station for rescue, theoretical analysis and numerical simulation were used to study the smoke diffusion law in the rail area and platform layer of the station when the fire train slowed down to stop under different smoke control measures, and the influence of the fire prevention and ventilation system of the station under this scenario was defined. The results show that the smoke distribution in the upper and lower reaches of the fire train is affected by the characteristics of moving fire source and piston wind. Although the shielding door can effectively prevent the smoke from spreading to the platform, it will increase the piston wind speed in the rail area and increase the smoke spreading speed, which is not conducive to the safe evacuation of passengers. The smoke discharge effect in rail area was limited by the influence of piston wind, and the total smoke discharge efficiency decreased by 14%,and the smoke exhaust valves in the lower reaches of fire are more efficient.

Key words: underground station, train fire, numerical simulation, smoke diffusion, exhaust valve