自然通风城市隧道火灾温度分布试验研究

Experimental Study on Temperature Distribution Under Fire Circumstance in Natural Ventilation City Tunnel

设定了两种火灾规模,以1∶10模型比例对南京市某自然通风城市隧道进行了火灾时隧道内温度场的分布规律的模拟试验。试验结果表明,在大火灾强度下,温度场纵向影响范围相应增加;在隧道两口部存在温差的情况下,隧道内烟气主要向口部温度较高一侧的通风口扩散;在烟气经过通风竖井之后,烟气的温度有显著降低,证明自然通风竖井能够排出大量的烟气,并带走大部分热量,烟气会因热动力不足而发生沉降现象。

A fire testing was conducted in a natural ventilation city tunnel in Nanjing. The scope of the testing included temperature distribution of hot smoke under fire circumstance in the tunnel. The testing was carried out in a 1：10 scale model and two different fire loads were used to simulate in the experiment. The results indicated that the influential length of temperature distribution of hot smoke in the tunnel increase significantly along with the increase of fire load. Furthermore, the majority of hot smoke in the tunnel diffused toward the side whose temperature was higher when two exits of tunnel had difference in temperature. After hot smoke traversed ventilation shafts,the temperature of hot smoke obviously decreased. It proved that natural ventilation shafts can expel a mass of smoke from the tunnel and take off the majority of heat. Smoke can deposit due to the lack of heat motivity.