青藏铁路多年冻土区涵洞基础的冻融变形特征

Deformation characteristics of culverts in permafrost regions of Qinghai-Tibet Railway

对青藏铁路沱沱河试验段两座拼装式涵洞进行了地基地温及冻融变形监测,分析了涵洞多年冻土上限处的地温变化及地基的冻融变形特征。结果表明:涵洞地基的变形随地温的年波动变化,可分为冻胀和融沉两部分。冻胀变形小于下沉变形,涵洞基础的变形整体上表现为渐减沉降的特征;铁路路基及涵洞的修建改变了多年冻土原来的水热平衡,使涵洞多年冻土上限处地温产生正温波动,冻土上限产生变化,导致了涵洞地基土体沿涵洞纵向的不均匀变形。

Based on the monitoring of two culvert＇ s ground temperature and deformation in Tuotuo River test section along Qinghai-Tibet Railway, deformation characteristics and the variation of temperature of permafrost table under culvert were analyzed. The results show that the deformation of the culvert consists of frost iheave and thaw settlement in a year with the change of ground temperature, and the deformation has a characteristic of gradually slowdown settlement because the whole frost heave is smaller than the whole settlement. The construction of railway embankment and culvert changes the original water-heat balance of the permafrost region, thus resulting in the variation of permafrost level and non-uniform deformation along culvert＇ s axis.