Performance-based Fire Safety Analysis Of Subway Under The Influence Of Piston Wind

Along with the city to speed up the process,the traffic problem is increasingly serious.For its convenience,high efficiency and energy saving,the subway has become an effective way to solve the problem of congestion in the city.But at the same time,it brings some serious fire safety problems.For subway fire,the piston wind formed in subway train operation will have a certain impact on it,but at present,there is still very little research on the influence of piston wind on subway interval tunnel fire and subway station tunnel fire.Therefore,it is of great significance to analyze the safety performance of subway fire under the influence of piston wind.In this paper,the fire simulation software FDS is used to carry out the numerical simulation of subway tunnel fire with 3.6m × 1.2m × 1.4m built-in chamber under the action of piston wind in 6m × 1.5m × 2m tunnel.The rationality of the FDS model is verified by comparing with the maximum flame temperature and mass loss rate of the experimental results.Then,the numerical model of full-size subway tunnel fire under the influence of 1500 m piston wind is established,and the piston wind speed is changed,and the safety performance of subway tunnel fire under different piston wind speed(0,2 m/s,3m/s,4m/s)is analyzed.The results show that for the subway tunnel fire in 7.5MW,when there is no piston wind,the safety of the fire source downwind direction 50 m on the evacuation channel is the worst,and when the piston wind is 2m/s,3m/s or 4m/s,the safety of the fire source downwind direction 100m is the worst,and the greater the piston wind speed is,the worse the safety is.In the end,the numerical model of full-size subway station tunnel fire under the influence of piston wind is established,the piston wind speed(0,4m/s,5m/s,6m/s)and piston wind direction are changed,and the fire safety performance analysis of subway station tunnel under different piston wind speed and wind direction is carried out.The results show that for the subway station fire in 7.5MW,the safety on both sides of the platform is the worst,and the safety at the upper wind staircase is worse than that at the downwind staircase.When the piston wind is from the tunnel of ignition train side of the island platform,the greater the piston wind speed,the worse the safety in the platform.When the non-ignition train side tunnel in the island platform enters the piston wind,the safety in the platform is related to the position of the measuring point,and the wind speed of the piston does not have a simple negative correlation with the wind speed of the piston.