中文摘要：

为了解发生火灾后，顶棚设有烟道的隧道结构对人员逃生是否有利，采用火灾动力学数值模拟软件FDS，对热释放速率为20MW的中等火灾规模进行模拟，着重分析了烟道设置以及烟道口处排风风速变化时的烟气蔓延和温度分布情况．结果表明：在现有的隧道顶部加烟道将提高整个隧道顶部的烟气浓度，内侧烟气浓度从40mg／m^3提高到120mg／m^3，外侧提高到100mg／m^3；烟道口处设排风可加速烟气进入烟道，使得离火灾发生位置最近的两个烟道口外侧的烟气浓度和温度大大降低，提高了人员逃生的安全系数；当排风风速为2．5m／s时，300S后排风口外侧的CO含量开始趋于常数且低于13×10^-6（体积分数），该浓度下人员可顺利逃生，同时可使得火灾发生时消防人员可从上、下游两个方向对火灾进行扑救；该种隧道结构下发生火灾时必须保证只有2个烟道口处于开启状态．

英文摘要：

In order to reveal the effect of a tunnel with Fire Dynamics Simulator （FDS） is used to simulate a ceiling flues on personnel evacuation in fire, the software of medium-scale fire with a heat release rate of 20 MW. The smoke pervasion and temperature distribution varying with the flue-outlet exhaust velocity and the flue setting are then analyzed in detail. The results show that （ 1 ） the setting of ceiling flues improves the smoke density in the tunnel from 40mg/m^3 to 120 mg/m^3 inside the flue outlet and to 100 mg/m^3 outside the outlet; （2） the exhaust at smoke outlets accelerates the moving of smoke from the tunnel into the flue, and greatly reduces the smoke density and temperature outside the two flue outlets near the fire source, thus increasing the safety coefficient for personnel evacuation ; （3） at an exhaust velocity of 2.5 m/s, the volume fraction of CO outside the flue outlet approximates to a constant less than 13 ×10^-6 after 300s, which offers a relatively safe space for personnel evacuation and fire rescue from both the upstream and the downstream; and （4） for the tunnel with ceiling flues, only two flues can be unlocked when a fire occurs.