保温护道对冻土路基地温特征的影响

Influences of Insulating Berm on Ground Temperature Characteristics of Permafrost Subgrade

根据青藏公路昆仑山段实际地温观测数据与工程地质特点,建立了路基温度场模拟计算的数学物理模型及其边界条件,运用有限元方法模拟保温护道对路基温度场的影响,并结合青藏公路保温护道段工程试验研究,通过对比分析研究了保温护道对路基地温特征的影响规律。结果表明:修筑保温护道在一定程度上恢复了青藏公路在以往修筑过程中就地取土所破坏的路基两侧冻土环境,对防止融化盘的扩大,减少与减缓路基病害的发生与发展起到了十分积极的作用;相对于未遭破坏的天然地表而言,保温护道表面条件不利于冻土生存,冻土退化趋势有所加强。从路基热稳定性的角度,设置保温护道虽能有限度地缩小融化盘,其同时增大融化深度并提高年平均地温。人为上限、年平均地温及融化盘等路基温度场特征要素对设置保温护道反应不敏感,因此工程中不应将保温护道作为提高路基热稳定性的主要措施。

According to observation data of ground temperature and geological properties at Kunlunshan region of Qinghai Tibet highway, mathematic and physical model and its boundary conditions which were applied to simulate temperature field in subgrade were established. Influences of insulating berm on ground temperature characteristics in subgrade were simulated by finite element method and the rule was analyzed. Researches indicate that from the viewpoint of subgrade thermal stability, installing insulating berm can decrease thaw bowl to a certain degree, but thaw depth increases and mean annual ground temperature rises at the same time; in addition, artificial upper limit, mean annual ground temperature and thaw bowl are not sensitive to insulating berm so insulating berm shouldn＇t be regarded as main measure to improve thermal stability of subgrade and insulating berm doesn＇t help to thermal stability of subgrade.