Fire Diffusion And Safety Evacuation Of Subway Station

Subway,as an important transportation tool for urban residents,brings convenience,fast and efficient transportation to urban residents.It also contains many security risks because of its relatively closed space,large human flow and limited number of entrance and entrance.Especially when the subway fires,the fire spread quickly and the smoke cannot be eliminated in time.Fire prevention and fire extinguishing are difficult.Facing the threat of high temperature,heavy smoke and poisonous gas,when people escape,it is very easy to cause group casualties.Therefore,it is very important to study the diffusion of fire and the evacuation of people in the subway fire.The optimization and improvement of the safety evacuation design for the personnel of the subway station and the establishment of an effective emergency evacuation plan have become the focus of the scholars in various countries.This paper studies the subway station fire from two aspects.First,through the simulation of the subway fire through Pyro Sim,four fire situations are set up.In different situations,the production and diffusion of fire combustion products are analyzed quantitatively,According to the set safety standard,the shortest Available Safety Egress Time is calculated,and then the Pathfinder software is used to simulate the process of safety evacuation,and the Required Safety Egress Time and the Available Safety Egress Time are compared in the experiment to determine whether the safe evacuation can be carried out finally.By analyzing the data of fire spread and evacuation in four kinds of fires,the following conclusions can be reached:(1)when the heat release rate is 5000 k W,the ventilation speed increases from 1.5m/s to 3m/s,the smoke concentration decreases by 13.9%,t he CO concentration decreases 18.8%,the flue gas temperature decreases by 18.7%,and the ventilation speed has a significant influence on various factors.(2)When the heat release rate increased from 5000 k W to 20000 k W,the smoke concentration increased 3.6 times,the flue gas temperature increased by 1.5 times,the CO concentration increased by 1.5 times,during the evacuation process,4 people did not complete evacuation;The heat release rate of the 20000 k W remained unchanged,the ventilation speed increased from 1.5m/s to 3m/s,the smoke concentration decreased by 6.7%,the CO concentration decreased by 8.4%,and the flue gas temperature decreased by 8.3%.The personnel were all evacuated to the safe area again.It is found that when the heat release rate is large,although only increasing ventilation speed has little influence on the smoke emission but has significant influence on the evacuation time,the data show that the overall evacuation time is shortened by 20.1%,which greatly improves the possibility of safe evacuation.(3)When the heat release rate is constant,as the speed of ventilation increases from 1.5m/s to 3m/s,the available safe evacuation time will change with the difference of the location of the fire source.Outside the fire source 20 m,the safe evacuation time can be increased by more than 5 s,the fire source is within 20 m,and the safe evacuation time is almost no obvious change.