岩后隧道火灾内部特征温度影响范围研究

Study on the influence region of characteristic temperature in tunnel fire in Yanhou tunnel

为量化隧道内部发生火灾后的特征温度影响范围,以人眼高度的特征温度(70℃)和顶棚高度处的特征温度(334℃)作为影响范围界定参数。采用FDS数值模型方法研究了岩后隧道事故中单火源、多火源情况下的温度分布规律。研究结果表明:隧道中心线位置,无论是单火源还是多火源,人眼特征高度处的温度影响范围皆小于顶棚处温度影响范围。多火源时,在相邻火源区域间,人眼特征高度处温度出现明显叠加效应,而顶棚高度处则未出现该现象,但其区域内温度远高于人眼特征高度处,且衰减所需时间更长。以464 m长的岩后隧道为研究对象,30 s后距离第一火源50 m范围内的汽车已经达到可燃温度,360 s后距离第一火源184 m的煤车尚未达到可燃温度。人眼特征高度处烟流叠加区域温度呈现出极不稳定的动态升高,但最高温度较顶棚处低。叠加区域以外,顶棚处温度衰减比人眼特征高度处更为缓慢,但影响范围会持续扩大,受时间效应影响明显。

In order to quantify the influence range of characteristic temperature after fire in tunnel, the characteristic temperature at eye height(70 ℃) and the characteristic temperature at ceiling height(334 ℃) are taken as key parameters of influence range. The temperature distribution rule of single and multiple fire sources in Yanhou tunnel accident was simulated by FDS numerical method. Results show that the influence range of temperature at eye feature height is smaller than that at the ceiling height, regardless of single or multiple fire sources. In the case of multiple fire sources, the superposition effect of the temperature obviously appears at the eye feature height between adjacent fire sources, while this phenomenon does not occur at the ceiling height. And, the temperature in the region is much higher than that at the eye feature height, the decay time is longer. In Yanhou tunnel with length of 464 m, the cars within 50 m from the first fire source has reached ignition temperature after 30 s,and the coal car 184 m from the first fire source does not temperature after 360 s. At the eye feature height, the temperature of smoke presents a highly unstable dynamic increase in superposition region, but the maximum temperature is lower than that at the ceiling. Outside the superposition area, the decay of temperature at the ceiling is slower than that at the eye feature height, but the influence region is still expanding in dependent of time consuming.