Abstract: In order to study the stability of embankment of the Qinghai-Tibet Railway after its operation, long-term monitoring system for the railway in permafrost regions was built in 2005. Monitoring content mainly includes ground temperature and deformation of the embankment. Ground temperature was monitored automatically with data collecting instrument; and deformation was obtained manually. Based on in-situ monitoring data of deformation and ground temperature from 34 embankment sections of Qinghai-Tibet Railway in permafrost regions during the year of 2005-2011, the characteristics and causes of deformation are analyzed. The results indicate that the accumulative deformation for a part of common embankments is more than 100 mm, respectively, which mainly comes from thaw settlement of permafrost with high-ice content and consolidation settlement of thawed soil because of the decline of permafrost table, as well as the compression deformation of warm permafrost due to rise of ground temperature under the embankment. For another part of common embankments and the crushed rocks embankments, owing to the compression deformation of permafrost under the embankment their total deformations are less than 100 mm, respectively. In general, the settlement deformation amount of crushed rocks embankments is remarkably less than that of common embankments, which confirms long-term effectiveness of the active cooling measure.

Key words: Qinghai-Tibet Railway, permafrost, embankment deformation, settlement