冻土路基护道地温特征研究

STUDY ON GROUND TEMPERATURE CHARACTERISTICS OF EMBANKMENT BERM ON PERMAFROST

一般地区路基工程设置护道是从边坡的力学稳定性方面考虑的,青藏公路整治改建期部分路段设置护道隔阻路基坡脚处积水,护道因具有保温作用而被称为可保温护道,青藏铁路建设参照青藏公路也设置了保温护道。为研究护道对冻土路基温度特征的影响,根据青藏公路试验工程地质特点,运用数值模拟方法计算路基温度场,并进行试验工程测温孔实际观察数据的对比分析,系统地研究了冻土路基护道地温特征变化规律。研究结果表明:设置护道对人为上限、年平均地温及融化盘等路基地温特征影响有限,但融化深度、年平均地温均表现为增大趋势;高温冻土区护道会加剧路基下冻土退化;冻土路基护道不应作为提高路基热稳定性的主要措施。

A common area of construction berm in subgrade project was considered based on the mechanical stability of slope. When Qinghai-Tibet highway is rebuilt, some sections of the highway construction berm to obstruct seeper in slope angle are adopted： and the berm could be used for heat preservation. Aiming to study the berm＇s effects of ground temperature characteristics of embankment on permafrost, numerical modeling was used to calculate the temperature field, according to the characteristic of the highway, comparative analysis and the research of the laws. It shows that construction berm has limit effect on the ground temperature characteristics of embankment such as artificial permafrost table, annual mean ground temperature and thaw bowl, however, the thaw depth well increase and annual mean ground temperature will rise. High temperature on permafrost berm could deteriorate the degeneration of the frozen soil under the embankment. The result indicates embankment berm on permafrost region should not be regarded as the main measure to improve thermal stability of embankment.