寒区隧道温度场变化规律及空气幕保温效果

隧道洞口段铺设保温层不能完全解决寒区隧道的冻害问题，为此提出一种新型寒区隧道空气幕保温系统，采用叠加原理、分离变量法和贝塞尔特征函数建立列车风影响下寒区隧道温度场计算模型，研究不同列车运行速度和运行间隔时寒区隧道温度场的分布规律，验证了新型寒区隧道空气幕保温系统保温效果. 研究结果表明:当外界气温为 ?30 ℃，围岩地温为5 ℃时，隧道洞口段铺设保温层已无法满足寒区隧道保温需求，应与主动保温措施联合；寒区长大隧道结构防寒不应仅在洞口段，若列车运行速度大（大于200 km/h）、列车运行频率高（间隔小于30 min），寒区长大隧道需要全隧道防寒；50 m的保温空气幕联合1 050 m的保温层可以满足外界气温为 ?30 ℃、围岩地温为5 ℃、列车运行速度为300 km/h、列车运行间隔为10 min这种极端情况下寒区隧道的保温需求. 

Temperature Field Law in Cold Region Tunnels and Insulation Effect of Air Curtain

Only laying thermal insulation layer in the tunnel portal section can not completely solve the frost damage problem in cold regions. Therefore, a new air curtain insulation system for cold region tunnels is proposed, a calculation model for temperature field in cold region tunnels subjected to train wind was employed by approaches including superposition principle, separation variable method, and Bessel characteristic function, the distribution law of temperature field in cold region tunnels with different train running speeds and running intervals was studied, the thermal insulation effect of the new air curtain insulation system in cold region tunnels was verified. Only laying thermal insulation layer in the tunnel portal section cannot satisfy the insulation demand for tunnels in cold regions when the ambient temperature is ?30 ℃ and the temperature of surrounding rock is 5 ℃, the active thermal insulation measures should be implemented. If the train running speed is more than 200 km/h and the train operation interval is less than 30 min, the whole tunnels need to prevent cold and heat preservation. Finally, it is proved that 50 m air curtain combined with 1050 m insulation layer can meet the thermal insulation requirement of tunnels in cold regions under extreme conditions.