超长公路隧道火灾纵向通风的烟气特性研究

Study on Smoke Characteristics of Longitudinal Ventilation for Fires in Very Long Highway Tunnels

目前公路隧道火灾纵向通风的研究主要集中在中、短隧道,针对5km以上超长隧道的研究成果较少,也缺乏相应的具体的设计指导准则。依托实际工程项目—大兴乡隧道,针对典型火灾场景(30MW),建立了超长隧道火灾全纵向通风的数值计算模型,研究超长隧道火灾全纵向通风的烟气特性。结果表明:超长隧道火灾烟气基本在火源下游1300m以外达到均匀分布,即下游1300m以外的烟气浓度不再随蔓延距离的变化而变化,而通风速度的增加有助于隧道烟气浓度的下降。研究的三种风速情况下,超长隧道火灾烟气均满足安全控制标准。

At present,the research on longitudinal ventilation for fire in road tunnels mainly focuses on medium and short tunnels,and there are fewer research results on super-long tunnels of more than 5 km,and there is a lack of corresponding specific design guidelines.In this paper,relying on the actual project-Daxingxiang Tunnel,for a typical fire scenario(30MW),a numerical calculation model of the full longitudinal ventilation of long tunnels with fire is established,and the smoke characteristics of the full longitudinal ventilation of long tunnels with fire are investigated.The results show that the smoke from a super-long tunnel fire basically reaches a uniform distribution beyond 1300m downstream of the fire source,i.e.,the smoke concentration beyond 1300m downstream no longer varies with the spreading distance;the increase of the ventilation speed helps the decrease of the smoke concentration in the tunnel;and the smoke from a fire in a super-long tunnel meets the safety control standards under the three wind speed scenarios studied in this report.