青藏铁路冻土与融区过渡段路基变形特性试验研究

Experimental Study of the Embankment Deformation in the Frosting-Thawing Transition Zone along the Qinghai-Tibet Railway

冻胀和融沉是影响寒区路基稳定性的两大问题.对于多年冻土到融区过渡段路基,除考虑冻胀和融沉外,还应考虑多年冻土区和融区路基沉降变形差和冻胀变形差问题.根据青藏铁路沱沱河试验段路基在竣工后3a内的现场试验数据,分析了有代表性路基的地温变化、路基基底变形以及整个试验段的冻胀、沉降变形差问题,计算出了多年冻土与融区过渡段路基的合理长度.结果表明:多年冻土与融区过渡地带沉降总变形量相差较大,但从年沉降速率来看,路基不会产生突降,且随着沉降速率逐渐减小,路基趋于稳定;试验段内冻胀量差异不大,不会影响线路平顺度.对于本试验段此类工程地质条件,可以采用允许多年冻土融化原则的工程措施.

The frost-heaving and thawing-settlement are the two aspects that affect the stability of embankments on cold regions.As for the embankment in frosting-thawing transition zone,the influence of deformation difference and settlement difference between permafrost zone and talik zone should be considered,in addition to frost-heaving and thawing-settlement.Analyzing the field test data of an embankment in the Tuotuohe Test Section of the Qinghai-Tibet Railway for 3 years after construction,the ground temperature variations of several representative embankments,the deformations of embankment basement and the deformation difference of total test section from frost-heaving to thawing-settlement were revealed.The reasonable length of the transition section was determined.It is found that the total deformation difference of the embankment between permafrost zone and talik zone is obvious.However,looking from the annual sediment rate,the embankment cannot settle suddenly,and will approach stability as the settlement rate decreasing gradually.The deformation difference in the frost-heaving section is not so evident and can not cause trouble to the track smoothness.The engineering principle that allows thawing of permafrost can be adopted for the engineering geological conditions similar to the Tuotuohe Test Section.