寒区隧道温度场分布规律及保温层适应性研究

为了研究寒区隧道的防寒保温设计问题,采用数值分析方法探讨不同外界气温、围岩地温以及有无保温层等条件下寒区隧道温度场的分布规律和保温层适应性研究,并采用叠加原理、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的计算模型,分析有无列车运行条件下寒区隧道温度场的变化规律。研究结果表明:由于二衬后出现负温分布对隧道衬砌结构安全性影响较大,因此建议将二衬后不出现负温分布作为寒区隧道保温措施的控制指标;在不考虑列车风影响条件下,保温层法最佳适用于最冷月平均气温为-2~-15℃的地区,当最冷月平均气温低于-15℃、围岩地温低于5℃时,保温层法应与主动保温措施相结合;当列车运行速度为300km/h、运行间隔为30 min时,通车与不通车相比隧道洞内中间位置平均气温下降约1.22℃,二衬后沿隧道进深方向出现负温的距离约增加36.8%。

Research on Distribution Law of Temperature Field of Tunnel in Cold Region and Thermal Insulation Layer Adaptability

In order to study the thermal insulation of tunnel in cold region,the numerical simulation method is used to identify the distribution law and thermal insulation layer adaptability of temperature field of tunnel in cold region under such different conditions as the ambient temperature,the ground temperature of surrounding rock,and the presence or absence of thermal insulation layer.According to the superposition principle,the separation variable method and the Bessel characteristic function,the calculation model of temperature field of tunnel in cold region under the influence of train induced wind is established,and the distribution law of temperature field of tunnel in cold region with orwithout train operation is also analyzed.The results show that,as the negative temperature distribution appearing after tunnel secondary lining has great influence on the safety of tunnel lining structure,no negative temperature distribution after tunnel lining structure is recommended as the control index of insulation measures for tunnels in cold region.Independence of the influence of train wind,thermal insulation layer method is most suitable for the area where the average temperature of the coldest month is between-2 DEG and-15 DEG;while the average temperature of the coldest month is lower than-15 DEG and the ground temperature of surrounding rock is lower than 5 DEG,thermal insulation layer method should be combined with active thermal insulation measures.When the train speed is 300 km/h and the operation interval is 30 min,the average temperature drop in the middle of tunnel is about 1.22 DEG with train operation compared with that without train operation,and the distance where negative temperature appears after secondary lining increases by about 36.8% along the length of the tunnel.