Fire Safety Assessment And Simulation Research On Water Mist System Of Subway Train

In recent years,with the growth of urban population,urban traffic pressure is also increasing year by year.Due to its fast and convenient,large passenger volume and pollution-free characteristics,metro has become one of the main forces to relieve traffic pressure in most cities,and is now in the stage of vigorous development.Due to the characteristics of concentrated personnel,narrow space and abundant equipment and materials in subway cars,when there is a fire accident,the fire is easy to spread in the car,and the high-temperature smoke will spread throughout the car in a short time,causing casualties,property losses and bad social impact.Therefore,it is necessary to analyze and discuss the key factors affecting the subway fire.Based on literature research and theoretical analysis,this paper analyzes the development and spread process of the fire in subway train by combining with the structure characteristics of subway car.The research on the fire load in subway cars mainly includes the number of fixed load,the distribution of fixed load and the arrangement of fixed load.And on this basis,the effect factors of metro subway fire safety indicators are summarized,after using the DEMATEL method to summarize the index factors for further screening,build a subway train fire evaluation index system,and combining with the Fuzzy Analytic Hierarchy Process(F-AHP)to determine the key value of indexes at all levels,an example of typical type B for subway train get the security status of the subway score is 70.85,shows that the state of vehicle safety,and fire control facilities scored lowest.Therefore,the fire fighting equipment and facilities can be used as the key factors to analyze the subway train fire.In order to further demonstrate the correctness of the evaluation results,FDS software was used to study the influence of water mist system on the fire development process in subway cars,which mainlyincluded the fire heat release rate,temperature distribution characteristics,flame and flue gas spreading process and flashover special fire phenomenon.The results show that,without the use of any fire fighting equipment and facilities,the flame will spread rapidly along the bottom of the ceiling,the whole carriage is enveloped by the high temperature smoke in a short period of time and the duration is long,at this time,the obvious flashover phenomenon occurs in the carriage,and the flashover intensity is different in each region.Under the condition of starting the fire extinguishing equipment with high pressure water mist,the spread of flame and smoke in the compartment is effectively restrained,and only the area close to the fire source has weak flashover.It shows that the fine water mist system can effectively restrain the development of fire in the carriage.