高海拔铁路隧道横通道火灾烟气扩散规律数值模拟

Numerical Simulation of Fire Smoke Diffusion Law in Cross Passage of High-altitude Railway Tunnel

为了得到高海拔双洞单线铁路隧道横通道内火灾烟气扩散规律,文章以某典型高海拔铁路双洞单线隧道为依托,采用FDS火灾动力学模拟软件,建立了隧道火灾燃烧模型,分析了高海拔隧道发生火灾时,横通道内温度及可视度的分布规律,研究了横通道间距及纵向自然风风速对高海拔隧道横通道内烟气扩散的影响规律。研究结果表明:隧道内高温主要集中在火源正上方拱顶处,随纵向扩散距离增加,火灾烟气温度快速衰减至常温;随火灾时间增加,烟气沉降所引起的人眼高度处可视度降低现象越发明显。当紧急救援站位于下坡段,横通道间距增加有助于减缓烟气向横通道扩散,纵向风速增大将导致横通道内温度上升,可视度下降,不利于疏散救援。当横通道间距与自然风风速耦合作用时,二者互相干扰,各自的作用规律不明显,但存在最不利工况,有烟气扩散至救援隧道内,横通道内人眼特征高度处最高温度为41.79℃,最低可视度为13.15 m,并未超过规范给定范围,人员可经横通道进行疏散。

In order to obtain the fire smoke diffusion law in the cross passage of higb-altitude double-tube singletrack railway tunnel,a typical high-altitude railway double-tube single-track tunnel was based on in this paper to establish the tunnel fire model by using FDS fire dynamics simulation software to analyze the distribution law of temperature and visibility in the cross passage of the high-altitude tunnel in case of fire and investigate the effects of cross passage spacing and longitudinal natural wind speed on smoke diffusion in the cross passage of the highaltitude tunnel.The results indicate that high temperature in the tunnel is mainly concentrated at the vault directly above the fire source.With the increase of longitudinal diffusion distance,the smoke temperature decays rapidly to normal temperature;the decrease of visibility at human eye height caused by smoke settlement becomes more and more obvious over time.When the emergency rescue station is located in the downhill section,the increase of cross passage spacing is helpful to slow down the diffusion of smoke to the cross passage,and the increase of longitudinal wind speed could lead to the increase of temperature and visibility in the cross passagi,which is not conducive to evacuation and rescue.When the cross passage spacing and natural wind speed are coupled and interfered with each other,their respective action laws are not obvious,but there is the most unfavorable case,that smoke might diffuse into the rescue tunnel.In the cross passage,maximum temperature is 41.79℃and minimum visibility is 13.15 m at the characteristic height of human eyes,which do not exceed the range specified in the specification,and persons could be evacuated through the cross passage.