长大公路隧道火灾温度场分布试验研究

为了掌握长大公路隧道内的火灾行为,提升秦岭特长公路隧道的火灾安全性,进行了火灾时隧道内温度场的纵向、横向分布规律及温度场扩散范围的大比例(1:6)火灾模型试验.模型隧道内径为1.8 m,长100 m.隧道内的风速在10 m/s范围内.试验中设定了3个火灾规模用以模拟实际的隧道火灾场景.试验中隧道内烟流温度通过CAN数据采集系统自动记录.试验结果表明,横向温度分布呈现拱顶最高,拱腰、边墙次之,底部最低的规律.对纵向温度分布而言,火区温度最高,随着远离火区温度逐渐降低.火灾规模及通风速度对温度分布及温度扩散范围具有明显的影响.随着火灾规模的增大,隧道内各点烟流温度及影响范围均增大.而随着通风速度的增大,温度扩散范围增大,火区最高温度降低,隧道内温度分布趋于均匀.此外,根据试验成果对结构防火措施、设备布置方案、火灾时通风风速的设定以及行车距离的限制等给出了合理的建议.

Experimental study of temperature distribution in long-sized road tunnel

To investigate fire behavior in tunnel and improve fire protection in the Qinling long-sized road tunnel,a series of fire testing were conducted.The scopes of the testing include temperature distribution and influential length of hot smoke in the tunnel under fire circumstance.The testing was conducted in a 1:6 scale model.The model tunnel had a circular cross-section with an inner diameter of 1.8 m and 100 m in length.Square fire sources were employed as model fire sources.The air velocity produced by the fans varied from 0 to 10 m/s in different tests.Three different fire loads were used to simulate different fire scenarios.Numerous thermocouples were installed at various cross sections within the tunnel to measure temperatures.Measurements were recorded continuously by the data acquisition system of controller area network.Results indicate that the maximum temperature locates near tunnel ceiling in transverse direction;as for longitudinal temperature distribution,the maximum temperature lies in fire source and the temperature of hot smoke decreases with the distance from fire source.Furthermore,the temperature distribution and influential length of hot smoke in the tunnel vary significantly with air velocity and fire load.The maximum temperature and influential length of hot smoke on tunnel users increase with fire load.The maximum temperature in fire source decreases and influential length of hot smoke increases when air velocity applied in tunnel increases.Based on the experimental results,suggestions on structure protection,criteria of equipment collocation,fire ventilation modes and vehicle controlling under fire scene are proposed.