公路隧道通风设计若干问题探讨

长大公路隧道的通风系统工程造价高、运营能耗大,通风系统设计合理与否,对长大隧道工程建设有重要影响。现行的《公路隧道通风照明设计规范》(JT J 026.1-1999)在隧道自然风阻力计算、根据稀释烟雾计算隧道需风量、竖井送排式通风系统中“不应有短道回流”等方面存在一定问题。在分析论证的基础上提出:(1)隧道自然风阻力应由自然风等效压差确定,在缺少工程实地观测资料的情况下,假定隧道自然风阻力为常量,并在10~30 Pa之间取值;(2)依据稀释烟雾计算隧道需风量时,在公式中应引入烟雾的质量浓度或烟雾的体积浓度,并用其替代公式中的一般烟雾浓度;(3)竖井送排式通风系统中宜变短道顺流为有控制的回流。

Discussion of Several Problems in Ventilation Design for Highway Tunnel

Whether the ventilation system is designed reasonable or not can significantly affects the construction of long highway tunnel for its high cost in economy and energy.There are several problems in the present Specification for Design of Ventilation and Lighting of Highway Tunnel(JTJ 026.1-1999),such as the calculation of the resistance caused by natural wind in tunnel,the calculation of the amount of fresh air required to dilute smog, and "no circumfluence is permitted in the short section" when ventilating by shaft.On the basis of analyzing and reasoning,the conclusions are reached as the following:(1) The resistance caused by natural wind in tunnel is determined by equivalent pressure difference of the natural wind,and should be assumed to a constant value between 10 and 30 Pa if no observation data is available;(2) When calculating the amount of fresh air required to dilute smog,mass or volume concentration is introduced into the formula to replace the old smog concentration;(3) When ventilating by shaft,it is more reasonable to permit a controllable circumfluence than no circumfluence in the short section.