寒区隧道洞口段空气幕保温理论研究

Theoretical Research on Air Curtain Insulation of Tunnel Portal Section in Cold Region

为保证寒区隧道在服役期间不发生冻害,根据相似原理搭建隧道温度场模型试验台,研究寒冷季节隧道内温度的变化规律,并提出一种新型的主动保温措施-隧道洞口段空气幕保温措施。使用流函数叠加与热平衡原理,得出空气幕保温措施的控制方程,使用叠加原理及贝塞尔特征函数推导出在空气幕作用下,寒区隧道洞口断面处围岩的径向温度解析解,最后以正盘台隧道为算例,验证该保温措施的可行性。研究结论表明:外界环境温度和围岩温度是影响寒区隧道温度场的主要因素;采用控制方程计算,图像结果显示空气幕保温措施可有效防止隧道冻害;隧道径向温度理论解与有限元计算结果相差较小,解析法可为今后的工程实践提供理论基础。

In order to prevent the tunnels in cold regions from freezing damage during the service period,a model test bed for the temperature field of the tunnels was built according to similar principles to study the changes in temperature in the tunnels in cold season,and a new active thermal insulation method,air curtain insulation measure at the tunnel portal section,was proposed.Based on the principle of stream function superposition and heat balance,the control equation of air curtain insulation measures was obtained.The superposition principle and Bessel eigen function were used to derive the analytic solution of the radial temperature of the surrounding rock at the tunnel portal section in the cold region under the action of the air curtain.Finally,based on the example of Zhengpantai tunnel,the feasibility of the thermal insulation measures was verified.The results show that the external environment temperature and surrounding rock temperature are the main factors affecting the temperature field of tunnels in cold regions.Using the control equation calculation,the image results show that the air curtain insulation measures can effectively prevent the tunnel from freezing damage.There is a small difference between the theoretical solution of the tunnel radial temperature and the finite element calculation results.The analytical method can provide a theoretical basis for future engineering practice.