超长高海拔公路隧道火灾烟流扩散及温度分布规律

Laws of Smoke Diffusion and Temperature Distribution in Super-long High-altitude Highway Tunnel on Fire

天山胜利隧道全长22 km,是目前世界最长的在建高海拔高速公路隧道。采用FDS(fire dynamics simulator)软件火灾动力学计算模型模拟了不同通风条件下海拔高度2850 m的天山胜利隧道火灾发展过程,明确了不同通风条件下天山胜利隧道内火灾烟流的扩散规律以及温度的时空分布规律,提出了主隧道烟气的控制标准。结果表明:①考虑天山胜利隧道车型比例、多车辆串燃以及高海拔环境等因素,确定天山胜利隧道火灾火源规模折减为22 MW;②当隧道不通风时,火源上方拱顶温度由于隧道坡度影响,具有明显先增大后衰减的趋势,相比于无坡度条件下,前者达到最高温度快,且最高温度低;③隧道内温度随着通风速度的增加和远离火源而降低,隧道内可视度随着远离火源先增加后减小、随着风速增加而增大;④随着风速增加,人眼特征高度处温度高于60℃、可视度低于10 m的范围逐渐减少;⑤主隧道坡度为1.367%对应的火灾控烟临界风速为4 m/s,横通道坡度为-7.5%时无通风条件下进本无烟气进入。

With a total length of 22 km,the Tianshan Shengli Tunnel is the world s longest high-altitude highway tunnel under construction.The FDS fire dynamics calculation model was used to simulate the fire development process of the Tianshan Shengli Tunnel at an altitude of 2850 m under different ventilation conditions,and the diffusion law of fire smoke flow and the space-time distribution law of temperature in the Tianshan Shengli Tunnel without ventilation conditions were defined.The results show these as follows.Considering the proportion of vehicles in Tianshan Shengli Tunnel,multi-vehicle tandem burning and high altitude environment and other factors,the fire source scale of Tianshan Shengli Tunnel fire was reduced to 22 MW.When the tunnel is not ventilated,the temperature of the vault above the fire source increases firstly and then decreases obviously due to the influence of the tunnel slope.Compared with the condition without slope,the temperature of the vault above the fire source reaches the maximum temperature faster and the maximum temperature is lower.The temperature in tunnel decreases with the increase of ventilation speed and distance from fire source,while the visibility increases first and then decreases with the distance from fire source,and increases with the increase of wind speed.With the increase of wind speed,the range of temperature above 60℃and visibility below 10 m at the height of human eye feature gradually decreases.When the slope of the main tunnel is 1.367%,the critical wind speed of fire smoke control is 4 m/s.When the slope of the transverse passage is-7.5%,there is no smoke entering the main tunnel under the condition of no ventilation.