CHARACTERISTICS OF THAWED INTERLAYER BENEATH EMBANKMENT OF THE QINGHAI-TIBET RAILWAY IN PERMAFROST REGIONS

Based on the data of ground temperature and deformation beneath embankment of the Qinghai-Tibet Railway in permafrost regions during the year 2006 to 2013, characteristics of thawed interlayer beneath the embankment and its effect on the embankment settlement deformation are studied. The results indicate that there is little thawed interlayer developed beneath natural field along the Qinghai-Tibet Railway, while beneath the embankment the thawed interlayer is developed widely, and it can be refrozen totally in the regions of lower mean annual ground temperature and developed further in the regions of higher mean annual ground temperature. The increasement of thickness of thawed interlayer in warm permafrost regions was duo to the decreasing of artificially permafrost table. Thawed interlayer is closely related to the embankment settlement deformation. The ice content of permafrost under the thawed interlayer controls the settlement deformation of embankment, the higher the ice content is, the bigger the settlement deformation is.