水下隧道出入口大纵坡段侧壁排烟控制策略研究

Study on Smoke Exhaust Control Strategy of Side Wall in Large Longitudinal Slope Section of Entrance/Exit of Underwater Tunnel

当水下隧道出、入口大纵坡段发生火灾时,受烟囱效应影响,火灾烟气向上坡方向扩散,导致火源上下游烟气分布不均匀,不利于侧壁排烟,其排烟策略有待研究。文章以苏锡常高速太湖隧道工程为例,建立FDS数值模型,通过对不同火灾规模、排烟模式及纵向补风条件下排烟效果进行对比分析,提出水下隧道出、入口大纵坡段火灾排烟控制策略。结果表明:(1)仅采用自然补风+侧壁排烟时,火源下坡侧远端排烟口效率较低,为了提高排烟效率,下坡侧可开启1处排烟口,上坡侧可开启5处排烟口;(2)开启射流风机,纵向补风风速控制为0.5~1.0 m/s,可有效提高侧壁排烟系统排烟效率,但对可用安全疏散时间并无明显改善;(3)纵向风速为3.5 m/s,风向为上坡方向时,可加速火灾烟气排向隧道外,增加可用安全疏散时间,保障人员逃生安全。

In case of a fire in the large longitudinal slope section at the exit/entrance of an underwater tunnel,the smoke from the fire.affected by the chimney effect,will spread uphill,resulting in uneven distribution of smoke upstream and downstream of the fire source,which is not conducive to side wall smoke exhaust.Its smoke exhaust strategy needs to be studied.Taking Taihu Tunnel Project of Suzhou-Wuxi-Changzhou Expressway as an example,the FDS numerical model is established in this paper.By comparing and analyzing the smoke exhaust effects under different fire scales,smoke exhaust modes and longitudinal air supply conditions,the smoke exhaust control strategy for large longitudinal slope sections at the exit/entrance of underwater tunnel is put forward.The results show that:(1)When only natural air supply+side wall smoke exhaust are used,the efficiency of the remote smoke vent on the downhill side of the fire source is low.In order to improve the smoke exhaust efficiency,one smoke vent can be opened on the downhill side and five smoke vents can be opened on the uphill side;(2)Turning on the jet fan and controlling the longitudinal air supply speed at 0.5~1.0 m/s can effectively improve the smoke exhaust efficiency of the side wall smoke exhaust system,but it shows no obvious improvement on the available safe evacuation time(ASET);(3)When the wind direction is uphill,the longitudinal wind speed of 3.5 m/s can accelerate the discharge of fire smoke out of the tunnel,increase the available safe evacuation time and ensure the safety of personnel escape.