Abstract: For tunnels in cold regions, in previous studies, the section with the lowest annual temperature of 0 ℃ in non-frozen section of tunnels in cold regions was generally regarded as the end point of thermal insulation layer laying. Based on the Zhihaidai highway tunnel in Qinghai province, with the help of finite element calculation software ANSYS, the direct coupling method was adopted to optimize the laying length of thermal insulation layer in the non-frozen soil section of Zhihaidai tunnel. The results show that it is more suitable to lay the thermal insulation layer of Zhihaidai tunnel with a length of 600m, rather than to lay the insulation layer to the place 650m away from the tunnel portal with an annual minimum temperature of 0 ℃. According to the characteristics of tunnel lining affected by freeze-thaw cycles, the freeze-thaw resistance and freeze-proof measures of tunnel lining in cold regions under freeze-thaw cycles were summarized. For tunnels in cold zone, the freeze-thaw cycle of lining can be improved by improving the frost resistance of concrete, setting up cold proof and heat preservation doors and installing snow proof shed. For Zhihaidai tunnel, by increasing the frost resistance grade of concrete to F800, the safety factor of lining structure will not be reduced during the operation period of 100 years.

Key words: tunnel engineering, cold region tunnel, safety coefficient, direct coupling method, thermal insulation layer, freeze-thaw cycles, anti-freezing measures of lining

摘要： 对于寒区隧道，以往的研究中，一般将寒区非冻土段洞内年最低气温为0℃的断面处作为保温层铺设的终点。依托青海知亥代公路隧道，借助ANSYS有限元计算软件，采用直接耦合法，对知亥代隧道非冻土段保温层铺设长度进行优化。结果表明：知亥代隧道保温层铺设长度为600 m更加合适，而非将保温层铺设到年最低气温为0 ℃的距洞口650 m处。根据隧道衬砌所受冻融循环作用影响的特点，总结了冻融循环条件下寒区隧道衬砌抗冻防冻措施。对于寒区隧道，可采取提高混凝土抗冻性能、设置防寒保温门和安装防雪棚等方式改善衬砌受到的冻融循环作用。对于知亥代隧道而言，将混凝土抗冻等级提高到F800，可使运营期100年间衬砌结构安全系数不减小。

关键词: 隧道工程, 寒区隧道, 安全系数, 直接耦合法, 保温层, 冻融循环, 衬砌防冻措施