Study On Synthetical Metro Fire Prevention Design Of Nujiang Park Station In Shenyang

As one of the important modern urban rail transportations, the subway bears much heavier transportation task. Some domestic and international subway fire accidents occur in recent years, what makes people realize the importance of the fire protection design of subway. In this paper, the Nujiang Park station of Shenyang subway line 9 is the research object, a FDS model is built to analyse the characteristics of the fire smoke spread and the plugholing phenomenon, by using the CFD(computational fluid Dynamics) software FDS(Fire Dynamics Simulator) and the filed data from a field investigation. To improve the formula of evacuation time and verify the safety of the evacuation, the scene of an evacuation is set by the set software Pathfinder. The specific research contents and conclusions are as follows:(1)The field investigation of Shenyang subway: The air speed is usually 0~1m/s at the stairs of the entrance or the exit, but the highest speed can reach 1.25m/s. The passenger flow volume is 96 persons per minute upstairs. The average value is between 3412 and 3787 persons per hour.(2)By building the FDS model of Nujiang Park station of Shenyang subway and setting a variety of exhaust modes, get following simulation results: The vertical walls can stop the smokes from flowing into the station hall effectively. It is a disadvantage of smoke emissions when the exhaust under the rail is open. When the fire intensity is 2.5MW at the platform, the critical exhaust air flow is 32.4m3/s that can meet the safety and specification requirements.When the fire intensity is 7.5MW in the rail area, the critical exhaust air flow is 80.4m3/s with the smoke ventilator above railway open. With the design exhaust speed, the fire danger is not come yet within the simulating time 400 s.(3)Take the middle of platform of the Nujiang Park for an example. The plugholing phenomenon occurs at all smoke vents. The air speed of each vent can be more than 5m/s under the design flow of exhaust. At this time, the exhaust efficiency is 21.738%. The critical air speed is between 3.2m/s and 3.5m/s, when the plugholing phenomenon occurs. As the increase of the number of exhaust vents, the efficiency increases first and then decreases, the peak value is 34.644%. It is a suggestion that adding one or two exhaust port at each side of the platform.(4)Simulate the evacuation of Nujiang park station at peak hour and extreme circumstance using Pathfinder software. Evacuation numbers of the two scenarios are 2152 and 3107, and the evacuation time needed is 340 s and 358 s respectively. Occupants can all be evacuated safely before the fire danger coming. Suggest to change evacuation time in the specification from 6 min to 5 min.(5)Change the width of stairs, and back calculate a new stair capacity reduction factor which is 0.752 using 8 simulation results. Thereby, improve the evacuation time formula. Its applicability is verified by testing error.