封堵比例对隧道火灾顶棚温度分布的影响

Influence of sealing ratio on ceiling temperature distribution of tunnel fire

为掌握隧道火灾在封堵过程中火场的温度特性,搭建1∶10缩尺试验台,探究火源功率为12.67,18.24和24.83 kW下,采取封堵比例0%,25%,50%,75%和100%时,隧道顶棚温度的变化特征及衰减机制。试验结果表明:25%及50%封堵比例对隧道内升温影响较小,75%及100%封堵会出现温度突增现象,随着封堵比例的增加,隧道顶棚中心温度提前进入衰减阶段;火源功率只改变顶棚温度最大值,不影响温度纵向分布,火源中心区域升温速率高;封堵过程中下风侧顶棚温度纵向分布服从指数衰减变化,封堵比例与拟合系数b和温度衰减系数k之间呈线性拟合关系。

In order to understand temperature characteristics of fire field during sealing of tunnel fire,a 1:10 scale tunnel model was set up to explore temperature changes of tunnel ceiling and its attenuation mechanism with fire source power of 12.67,18.24,and 24.83 kW and sealing ratios of 0%,25%,50%,at 75%and 100%.The experimental results show that 25%and 50%sealing ratios have little effect on temperature rise in tunnel while 75%and 100%sealing will cause a sudden increase in temperature.As sealing ratio increases,temperature decay will come in advance.Power of fire source only changes the maximum value of ceiling temperature with no impact on longitudinal distribution of temperature,and heating rate in center of fire source is high.Temperature longitudinal distribution on downwind side attenuates exponentially during sealing,and it shows a linear fitting relation between sealing ratio and fitting coefficient b and temperature attenuation coefficient k.