寒区隧道冻害现象对工程结构稳定及运营安全构成了显著威胁，为探寻高效节能的保温方法，实现冻害的有效防治，基于离壁式保温法，充分利用空气的低导热性，建立一种全方位被动保温防冻基础模型，并提出配套的主动供暖措施，组成多种被动防寒与主动供暖相结合的防冻方法； 对其涉及的多场耦合进行理论分析，采用COMSOL Multiphysics数值模拟软件，对比探究相关被动-主动耦合防冻的节能保温性能，并据此提出一种融合被动防寒与主动供暖优势、实现二者协同增效的防冻方法。研究表明： 1）向离壁式空气层中通入速度0.5 m/s、温度1 ℃的热空气可避免仰拱上部衬砌冻害发生，隧道中部如有正积温空气，可直接引入使用，节能有效； 2）在中空保温结构管空气层中敷设线功率1.1 W/m的加热电缆，可保证管道水不冻结，相较于直接敷设加热电缆的节能效率达94.5%，同时避免了管道内部水对加热电缆的影响； 3）仰拱衬砌与保温层之间敷设的横向加热电缆最佳间距为2 m，拱脚设纵向辅助加热电缆可快速达到防冻效果。
Frost damage in tunnels located in cold regions poses a significant threat to the stability of engineering structures and operational safety. To address this challenge, a basic model for all-round passive insulation and anti-freezing is established using an off-wall thermal insulation method, fully considering the low thermal conductivity of air. Additionally, corresponding active heating measures are proposed, forming various anti-freezing methods that combine passive cold prevention with active heating. The involved multi-field coupling is theoretically analyzed. The energy-saving and thermal insulation performances of the passive and active coupling anti-freezing methods are compared and evaluated using COMSOL Multiphysics numerical simulation. Finally, an integrated anti-freezing method that combines the advantages of passive cold prevention and active heating is proposed, enabling their synergistic effect. The results show that: (1) Hot air with a velocity of 0.5 m/s and a temperature of 1 °C can prevent freezing damage in the upper lining and invert, and the positively accumulated temperature air in the middle of the tunnel can be directly utilized, resulting in an energy-saving and effective solution. (2) A heating cable with a line power of 1.1 W/m placed in the air layer of a hollow insulation structure pipe ensures that water inside the pipeline remains unfrozen, achieving 94.5% energy-saving efficiency compared with directly laying the heating cable, and preventing adverse effects from water on the heating cable. (3) The optimal spacing of the transverse heating cable laid between the invert lining and insulation layer is 2 m, and the longitudinal auxiliary heating cable set at the arch foot provides an effective anti-freezing effect.
