侧向排烟口对双层隧道机械排烟的影响

Influence of lateral smoke vent on mechanical smoke exhaust in double-decked tunnel

双层隧道具有空间利用率高,通行量大等优点,但由于顶部空间有限,多采用侧向排烟的方式控制隧道火灾时烟气的蔓延。以某越江隧道为例,采用火灾动态模拟软件FDS,改变排烟口数量、面积、间距,设计6个火灾场景,定量分析侧向排烟口的设置对机械排烟效果的影响。分析各排烟口流量、流速,分析隧道内温度分布、能见度分布。结果表明:在火源功率20 MW、无纵向风条件下,排烟口面积、排烟口开启数量以及排烟口间距都在火灾发生初期对烟气的蔓延起控制作用;提出在排烟口面积为4m2、排烟口间距为90m、火灾时开启4个排烟口时,排烟效果更经济合理。

Double-decked tunnels with the high space utilization and big traffic flow, was limited by the space on the top, so it usually choose the lateral pattern to control tunnel fire smoke spread. With the example of a tunnel through the river, setting 6 scenarios by varying the number and area and distance of smoke vent, FDS was adopted to analyze the influence of the lateral ventilation on the mechanical smoke exhaust quantitatively. The quantity and speed of flow at the vent, the distribu- tion of temperature and visibility in tunnel, were obtained. The paper proposed that the area, number and the distance of smoke vent can obviously impact the spread of fire smoke only in the early of the fire in the conditions of the fire power of 20 MW and no longitudinal wind; The design with the parameters as the smoke vent area of 4 m^2 , the distance of 90 m, and opening 4 smoke vents when fire, is more reasonable and economic.