Study On Factors Influencing Smoke Exhaust Effect When Platform Layer Or Station Hall Layer At A Subway Transfer Station In Fire

The subway has become the main measure to alleviate the traffic pressure of the city due to its large transportation volume,fast speed and no occupation of the above-ground space.The construction of subway lines in various cities has sprung up.In order to facilitate transportation,subway lines have increased,subway transfer stations have also increased,and the transfer station is in a closed underground space.The fire hazard is much larger than the ground space.Therefore,it is necessary to study the influencing factors of the smoke exhaust effect in the fire at the transfer station to ensure the safety of people’s lives and property.In this paper,the three factors of smoke vent height(H),smoke vent spacing(L)and smoke vnet velocity(V)in tHe ventilation system are studied when the fire occurs in the platform layer or station hall layer of a subway transfer station.So as to get the best smoke exhaust effect and corresponding parameter values.Firstly,using FDS(Fires Dynamics Simulator)software,a full-size subway transfer station model was established according to the drawing size of a subway transfer station.The model consists of a three-story structure:station hall layer,line A platform,and line B platform.Then,design of orthogonal experimental conditions based on orthogonal experimental principle.In this paper,there are three influencing factors of smoke exhaust effect in the subway transfer station fire.There are three hehehs of each factor,and nine working conditions are designed according to the orthogonal table L9(3~4).Finally,using FDS software to carry out numerical simulation,the smoke spread of the platform and the station hall under various working conditions,the temperature distribution of the human eye feature hevel,the CO concentration distribution,the visibility distribution,and the temperature distribution of the ceiling height layer are obtained.The index values under various working conditions was compared and analyzed and the best working conditions and corresponding parameters when exhausting smoke were obtained.Research indicates:(1)When a fire occurs in the station hall of the transfer station,the thickness and height of the smoke layer are small under working conditions 7(H=4m,L=8m,V=5.5m/s),the temperature value,CO concentration value and visibility value of the human eye feature level meet the safety evacuation standard,and the temperature value of the ceiling height layer also meets the safety evacuation standard.Working condition 1(H=3.2m,L=8m,V=4.5m/s)the safety of the above indicators is poor.(2)When there is a fire in the line A platform of the transfer station,the thickness and height of the smoke layer are small under working conditions 7(H=4m,L=8m,V=2.5m/s),the temperature value,CO concentration value and visibility value of the human eye feature level meet the safety evacuation standard,and the temperature value of the ceiling height layer also meets the safety evacuation standard.Working condition1(H=3.2m,L=8m,V=1.5m/s)the safety of the above indicators is poor.(3)When there is a fire in the line B platform of the transfer station,the thickness and height of the smoke layer are small under working conditions 7(H=4m,L=8m,V=2.5m/s),the temperature value,CO concentration value and visibility value of the human eye feature level meet the safety evacuation standard,and the temperature value of the ceiling height layer also meets the safety evacuation standard.Working condition1(H=3.2m,L=8m,V=1.5m/s)the safety of the above indicators is poor.It can be seen that when the subway transfer station is in a fire,the smoke exhaust effect under the condition of working condition 7 is the best.This paper provides a reference for the design of the exhaust vent height,the exhaust vent spacing and the exhaust vent velocity in the ventilation system of the subway transfer station.