Study On Smoke Movement And Smoke Control Of Atrium-Style Metro Station Fire

As a special kind of underground building,atrium-style metro station,compared with ordinary metro station,the confined space is broken and a shared space is formed.In case of fire,smoke tends to form a chimney effect and the risk of smoke spreading from the platform fire to the station concourse level increases,causing difficulties for evacuation.In order to investigate the influence of the smoke movement law and the key parameters and effects of smoke evacuation in atrium-style metro station,a 1:10 double-opening large atrium-style metro station small scale fire experiment platform was built.84 sets of small-scale fire experiments were carried out under different conditions of fire power,fire source location,smoke evacuation volume and drape curtain height,and the temperature data under the roof of the platform and station hall as well as in the vertical direction of the station hall were recorded to investigate the atrium type underground station fire movement law.The results of the study are useful for revealing the smoke movement patterns of atrium-style metro station,analyzing the influence of various factors on smoke movement,and determining the optimal smoke control parameters and measures for atrium-style metro station.The results of the study are of great significance in revealing the smoke movement characteristics of atrium-style metro station,and provide technical references for smoke prevention and evacuation design,personnel evacuation,and emergency rescue.The main research results include:(1)The pattern of smoke movement from fires in atrium-style metro station without mechanical smoke extraction.This paper analyses the effect of different fire source powers and fire source locations on the smoke movement of atrium-style metro station platform fires in the absence of mechanical smoke extraction.The results show that:the higher the fire source power,the higher the overall smoke temperature in the station hall and the faster the smoke movement;when the fire is located at different locations on the platform level,the smoke movement path is different:when the fire source is located in the platform area between the two atriums,the smoke hits the platform roof and then spreads horizontally along the platform When the source of fire is located in the station area between the two atriums,the smoke hits the roof of the station and then spreads horizontally along the roof of the station,moving through the atrium towards the station concourse,forming a balcony overflow plume,at this time,apart from the area of fire,the smoke mostly collects in the atrium area of the station concourse and the station concourse area between the two atriums;when the source of fire is located in the right atrium,the smoke is not blocked and forms an axisymmetric plume,hitting the roof of the station concourse and forming a roof jet,spreading horizontally under the roof of the station concourse,at this time,apart from the area of fire,the smoke mostly collects in the In addition to the fire area,most of the smoke gathered in the atrium area of the station hall.In addition,the smoke drops to a minimum clear height in the station hall within 3min,posing a threat to the evacuation of people.(2)The smoke movement law of atrium-type metro station under mechanical smoke exhaust conditions.Based on the above analysis,mechanical smoke vents were set in the roof of the atrium of the station hall,mechanical make-up air vents were set on both sides of the station platform,and drape curtains were set at the boundary of the atrium to analyze the influence of smoke extraction volume and height of drape curtains on smoke movement under mechanical smoke extraction conditions.The results show that:the larger the smoke exhaust volume under the established working conditions,the lower the overall temperature of the station hall,the better the smoke control effect,the maximum smoke exhaust volume can extend the time for the smoke to fall to the minimum clear height of the station hall by 30%,and the temperature rise achieved at the minimum clear height is reduced by 60%-70%.However,only the mechanical smoke vent can not effectively prevent the smoke from spreading to the minimum clear height of the station hall within 6min evacuation time,and smoke storage bins need to be installed to reduce the scope of the hazardous area of the station hall.The higher the drape curtain,the higher the temperature inside the smoke storage bin and the lower the temperature outside the bin,and the installation of drape curtains in atrium-style metro station can effectively accumulate smoke in the smoke storage bin and control the spread of smoke.Based on this,and taking into account the most unfavorable conditions,the use of a smoke extraction mode with smoke extraction from the station concourse and supplementary air from the station platform can effectively prevent the spread of fire smoke to the minimum clear height of the station concourse and ensure the safe evacuation of people,within a 6min evacuation time and a maximum fire power of 4.7MW.The specific smoke control scheme is as follows:four 3m×3m smoke vents are set in the roof of the atrium of the station hall,which are exhausted to the outdoors through smoke ducts,and fire shutters are set at the boundary of the atrium,and the fire shutters of the station hall area between the two atriums are lowered to the ground when a fire occurs,while the fire shutters of other areas are lowered to a height of2.6m on the ground and the smoke exhaust volume is not less than 156,000m~3/h,and then lowered to the ground after the evacuation of personnel is completed.Mechanical make-up air outlets are set up on both sides of the station platform,and the make-up air volume is 50%of the smoke exhaust volume.