热棒技术在国道214线共和-玉树高速公路宽幅冻土路基中应用的数值模拟研究

Numerical simulation study of the thermosyphon applied to wide embankment in permafrost regions of Gonghe-Yushu Expressway of National Highway 214

高速公路路基幅面宽度的成倍增加,沥青路面的吸热效应更为显著,工程对其下伏多年冻土的热影响更为显著.热棒、热棒保温板复合结构等传统工程措施能否保护宽幅高速公路下冻土稳定是一个亟待回答的问题.根据带相变热传导有限元方法,对共和-玉树高速普通路基、热棒路基和热棒保温板复合结构路基在未来全球变暖情形下的地温场特征进行了数值模拟分析.结果表明:在年平均气温为-3.5℃或地表年平均温度为-1℃的多年冻土地区,普通路基和热棒路基在全球变暖条件下路基下伏冻土都将发生融化,宽幅公路路基将会产生显著融沉变形,不能保证宽幅公路路基20 a使用期内的稳定性.热棒保温板复式结构显示了较好的冷却路基效果,在第20年路基下多年冻土人为上限高于原天然上限,路基下富冰冻土仍处于冻结状态,可以保证宽幅沥青公路在服务期内的热稳定性.

Expressways have a wide and high-temperature pavement, which leads to significant heat absorption and heat disturbance on underlying permafrost. It is the first concern to answer if some successful measures including thermosyphons can be applied to protect permafrost under. Using the finite element method and the threedimensional numerical analysis for the temperature characteristics of the common embankment, the embankment with two-phase closed thermosyphon and the embankment with both insulation and thermosyphon have been sim- ulated, considering the case where the air temperature increases 0.02 ℃ per year. It is found that the common embankment and the embankment with two-phase closed thermosyphon can not ensure the thermal stability of expressway embankment in permafrost regions where the yearly average air temperature is - 3.5 ℃, or the yearly average temperature on the original ground is - 1.0 ℃. However, the embankment with both insulation board and thermosyphon has virtues of insulation, achieving better effect of protecting permafrost, which is effective to decrease the underlying ground temperature and to ensure the stability of expressway with a wide and high-temperature surface with a service period of 20 years.