Study On Smoke Flow Simulation And Smoke Exhaust Mode Of An Island Subway Station In Xi'an

With the rapid development of underground rail transit in China,the mileage of China's subway has grown rapidly,but the painful lessons caused by the subway accident have also sounded the alarm.to us.Most of the subway accidents are caused by subway fires.It is a key link to reduce fire hazard to study the smoke flow rule of subway fire and take effective smoke evacuation measures to protect personnel safety.In this paper,based on the fire smoke spread in the middle of the subway platform,the physical model of the subway station is established by FDS software,and setting the different smoke exhaust modes during the fire occurrence.Simulation analysis of fire smoke emission effect in the middle of subway station platform and comparison of smoke emission effect of single fire smoke exhaust mode and mixed smoke exhaust mode with late visual processing.It reveals the flow law of fire smoke in the middle of subway station and the changes of related escape factors with different smoke exhaust modes.Provide reference for different smoke extraction modes when the fire occurs.The main research contents and results are as follows:(1)When a fire occurs in the middle of the subway platform,the flow of smoke and the factors affecting evacuation change by the natural smoke exhaust mode.The results show that under the natural smoke exhaust mode,the flue gas can spread to the station hall floor,and the smoke accumulated in the Upper part of platform makes the temperature,CO concentration and visibility of the platform level of 1.6m threaten the safety of escape personnel.It does not guarantee the safe evacuation of personnel.(2)When a fire breaks out in the middle of the subway platform,the smoke flow and the factors affecting evacuation change under the single smoke exhaust mode.The results show that under the single smoke exhaust mode,only the smoke exhaust mode of the public area station meets the needs of people to escape.The smoke evacuation mode of the station tunnel and Interval tunnel push-pull smoke exhaust mode are not able to meet the personnel's escape demand due to the low visibility.The double-pull interval tunnel affects the personnel escape speed by the excessive airflow velocity at the entrance of the elevator.(3)When a fire occurs in the middle of the subway station,the flow of smoke and the factors changes affecting evacuation in the mixed smoke exhaust mode.The results show that the mixed smoke exhaust mode can meet the needs of person escape.The joint smoke exhaust mode between the public area of the station and the station tunnel area can minimize the harm caused by the smoke to the human body.(4)The influence of downward airflow at escalator entrance on smoke spread was simulated.The results show that the relative position of escalator and smoke-proof vertical wall will affect the air flow velocity and direction from the hall floor to the platform floor,resulting in uneven distribution of smoke in the platform.It is difficult to achieve the downward airflow velocity of 1.5m/s at the escalator entrance section of the building,but as long as the downward airflow velocity at the downward edge of the smoke barrier is greater than 1.5m/s,the smoke can be prevented from entering the station hall floor.