地铁同站台高架换乘车站火灾全尺寸实验研究—(3)站台火灾

摘要

为了研究地铁同站台高架换乘车站台火灾情况,通过在某同站台高架换乘车站的大空间站台层区域开展0.25~1 MW规模的现场火灾实验,对烟气温度、烟气层高度和烟气蔓延时间进行分析,并建立了该类型车站站台区域顶棚烟气分布和烟气扩散时间的经验模型.研究结果表明:站台不同高度顶棚下方烟气温度呈指数分布趋势,且温度衰减速率随火源功率的增加而降低;受火源位置、顶棚结构和自然排烟的影响,站台层不同部位的烟气层高度有所差异,起火站台的烟气层高度在火源附近较高,在纵向方向呈逐渐降低的趋势,未起火站台火源断面位置处的烟气层高度较低,在纵向方向呈逐渐升高的趋势,现场应急救援和客流疏散中应充分重视未起火站台的危险性,同时防排烟设计应尽可能提高站台顶部排烟口总面积以降低烟气在扩散过程中的质量流量;烟气蔓延时间受火源功率的影响较大,在纵向方向与扩散距离呈线性增长趋势,随着火源功率的增加,烟气扩散速度逐渐升高,在0.25,0.5和1MW的火灾规模下烟气扩散速度分别为0.33~0.4,0.41~0.43和0.45~0.81m/s.%To study the fire in the one-platform-interchange elevated metro station,the field fire experiments with the fire size of 0.25-1MW were carried out at the large space platform area in a one-platform-interchange elevated metro sta-tion.The smoke temperature,smoke layer height and smoke spreading time were analyzed,and the empirical models of smoke distribution at the ceiling and smoke spreading time at the platform area of this type station were established.The re-sults showed that the smoke temperature at different heights under the ceiling of the platform presented the trend of exponen-tial distribution,and the decay rate of temperature decreased with the increase of heat release rate of fire source.Under the influence of fire source location,ceiling structure and natural smoke exhaust,the smoke layer heights at different positions of the platform were different.The smoke layer height near the fire source on the platform with fire was higher,and presented the trend of gradual decrease on the longitudinal direction,while the smoke layer height at the sectional position of fire source on the platform without fire was lower,and presented the trend of gradual increase on the longitudinal direction.The hazard of the platform without fire should be paid full attention in the field emergency rescue and passenger evacuation,and the total area of smoke exhaust vents at the top of the platform in the smoke control design should be increased as large as possible to reduce the mass flow of smoke in the spreading process.The smoke spreading time was significantly affected by the heat re-lease rate of fire source,and it presented the trend of linear increase with the spreading distance on the longitudinal direc-tion.The smoke spreading velocity increased gradually with the increase of heat release rate of fire source,and the smoke spreading velocity was 0.33-0.4 m/s,0.41-0.43m/s and 0.45-0.81m/s respectively with the fire size of 0.25 MW,0.5 MW and 1MW.