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为了研究青藏公路高温冻土区普通路基下部融化夹层的变化特征及其对路基沉降变形的影响,选取监测断面对路基地温与变形进行现场监测。结果表明:路基下最大融化深度出现在当年的10月份至次年的1月份,人为上限呈逐年加深的趋势。路基下最大冻深出现在当年的4—6月份,除右路肩外,左路肩和路中最大冻深呈波动中略有加深的趋势。路基下融化夹层厚度呈逐年加大的趋势,融化夹层厚度的增加主要是由人为上限的加深引起的。路基浅层温度的升高是融化夹层发育及下部多年冻土升温的主要原因。当融化夹层下部为高含冰量冻土时,融化夹层与路基沉降变形密切相关,路基易产生较大的沉降变形。当融化夹层下部为低含冰量冻土时,路基沉降变形较小。
In order to study the changing characteristics of the melting intercalation in the lower part of ordinary embankment in the permafrost zone of Qinghai-Tibet Highway and its influence on subsidence and deformation, the monitoring section was selected to monitor the site temperature and deformation of subgrade. The results show that the maximum melting depth under subgrade is from October of the current year to January of the following year, and the artificial ceiling is deepening year by year. Under the roadbed, the largest deep freezing appeared in April-June of that year. Except for the right shoulder, the maximum freezing depth of the left shoulder and road was slightly deepened. The thickness of subgrade melted interlayer increases year by year. The increase of melting interlayer thickness is mainly caused by the deepening of artificial ceiling. The increase of shallow subgrade temperature is the main reason for the development of melting interlayer and the temperature rise of the lower permafrost. When the lower part of the melting interbed is frozen ice with high ice content, the melting interlayers are closely related to the subsidence and deformation of subgrade, and the subgrade is easy to produce large settlement deformation. When the lower part of the melting interlayer is low ice content frozen ground, the subgrade settlement deformation is small.