Abstract: By the experiment on the existing railway station in Beijing, the smoke spread law and downdraft velocity under different smoke control conditions are analyzed. At the same time, the numerical simulation model corresponding to the actual size is established by FDS, and the working condition of smoke control mode change is added. Based on the available safe egress time judgment of the visibility, the smoke exhaust capacity in platform is studied. The results show that: for different smoke control modes, the smoke spreading law is not consistent. For the existing station, opening all fans and only opening No.1 fan will cause negative pressure at the staircase, that is, the smoke from the fire on the platform will not spread to the station hall; the analysis of the downdraft airflow velocity of the staircase section shows that the opening of all fans meets the requirements of the standard downdraft airflow velocity of the staircase of 1.5 m/s, while only opening No.1 fan, one side of the platform cannot meet the requirements of the standard; on the basis of the analysis of the smoke spreading law and the section wind speed, it is known that No.1 fan plays a main role in the station safety; combined with the test data of the staircase section wind speed and the simulated data of the available safe egress time judgment of the visibility, it is known that opening all fans greatly improves the safety of the station hall compared with only opening No.1 fan, but has little effect on the smoke exhaust capacity of the station.

Key words: existing subway station fire, smoke control mode, numerical simulation, smoke spread, downdraft airflow