高瓦斯隧道通风技术研究

Research on Ventilation Technology of High Gas Tunnel

超长公路隧道建设中,瓦斯浓度需作为施工安全因素考虑。以三联隧道为工程依托,采用流体计算软件PHOENICS建立了瓦斯隧道扩散数学模型,经计算研究共得出以下几点结论:在隧道横断面考虑,瓦斯浓度最高点为断面顶端,监测时需以顶端浓度作为判断依据;在隧道纵断面考虑,掌子面附近CH4浓度最高,瓦斯浓度最大,随着通入新鲜空气,瓦斯逐步向外扩散,掌子面位置瓦斯浓度降低;在入口风速为4 m/s条件下,通风30 min时刻掌子面CH4浓度降低至0.004 162,在入口风速为8 m/s条件下,通风30 min掌子面CH4浓度降低至0.002 301;从施工便利以及通风效果良好两方面考虑,最佳入口风速应设置为5~7 m/s。

In the construction of super long highway tunnel,the gas concentration should be considered as the safety factor of the construction. Based on the triple tunnel,calculation software PHOENICS to build the tunnel gas diffusion mathematical model with fluid,through calculation of the following conclusions： in consideration of the tunnel cross section,the highest point of the top section of the gas concentration monitoring,when need to top concentration as the basis of judging; considering the tunnel longitudinal section,near the tunnel face the highest CH4 concentration,gas concentration,with fresh air and gas gradually spread outward,the face position of gas concentration is reduced; in the entrance wind speed is 4 m/s under the condition of ventilation time 30 min face CH4 concentration decreased to0. 003 801,the entrance velocity is 8 m/s under the condition of the working face ventilation 30 min CH4 concentration decreased to 0. 003 801; considering the construction convenience and good ventilation effect in two aspects,the best entrance velocity should be set to 5 ~ 7 m/s.