Numerical study on the optimisation of smoke ventilation mode for interchange subway station fire

To effectively control smoke generated by fires in a single subway station, the traditional ventilation mode is usually adopted, which includes the lobby air supply system, the platform smoke exhaust system and the over track exhaust system. However, whether the existing traditional ventilation mode can effectively exhaust smoke under fire conditions in interchange subway stations is still unknown. In this paper, fire dynamics simulator software is utilised to study the efficacy of different ventilation modes on smoke confinement in a T-type interchange subway station connecting Line 1 and Line 2 of the Nanjing subway, and an optimised ventilation mode is proposed. The Tunnel Ventilation Fan (TVF) system is located in the tunnel but quite close to the two ends of the platform. The four fans are numbered in sequence as TVF 1-4. Results show that the optimised TVF operation mode is that TVF 1, 3 and TVF 2, 4 are in supply and exhaust mode, respectively, which forcedly forms one-way jet stream and plays a dominant role in smoke confinement. Meanwhile, the separate activation of lobby air supply system in Line 2 is conducive to assist the smoke control and obtains a better efficacy. It is better to deactivate the platform air supply system of Line 2. The optimal ventilation mode in a T-type interchange subway station is a combination of the traditional ventilation mode, the optimal TVF operation mode and the lobby air supply system of Line 2, which can effectively confine smoke and provide a safe evacuation path that is smoke-free.