不同吊顶形式的地铁站台火灾人员疏散环境分析

Analysis of Evacuation Environment of Pedestrian in Fire Condition at Subway Platform with Different Ceiling Types

以西安市某地铁车站岛式站台层为研究对象,利用火灾动力学模拟软件FDS,构建了3种不同吊顶形式(平板式、方形内凹式和格栅式)的站台层物理模型,在站台层5 MW火灾的情况下,对各个模型下烟气蔓延过程、吊顶层温度分布、人眼特征高度层温度分布、CO浓度分布和楼梯口处风速等与人员疏散环境相关参数进行了数值模拟,对比分析了3种不同吊顶形式下地铁车站站台层火灾的排烟效果。结果表明:方形内凹式吊顶可有效减缓烟气蔓延过程,降低楼梯口外侧烟气浓度,但会造成温度和CO浓度分布的局部波动;格栅式吊顶能提升烟气层高度,使人员疏散在火灾前中期处于更为安全的环境中,但烟气层过高不利于排烟口排烟。

Based on an island-type subway platform in Xi an City,this paper constructs three physical models of different ceiling types(flat,square concave and grille)by the dynamic simulation software FDS.The paper simulates the parameters of evacuation environment in the case of 5 MW fire at the platform,such as,the smoke spread process,the temperature distribution of the ceiling layer and the human eye characteristics layer,the CO concentration and the wind speed at the stairway in different models.Then,the paper compares the smoke exhaust effect of the subway platform in case of fire with the three ceiling types.The results show that the square concave ceiling can effectively slow the smoke diffusion process and reduce the smoke concentration outside the stairway,but it will cause the local fluctuation of the temperature and CO concentration;the grille ceiling can enhance the smoke height and provide a relatively safe environment in the early and middle stage of the fire,but overhigh smoke layer is unfavorable for smoke exhaust.