The deformation of normal roadbed is mainly controlled by compaction of soils

but that of the permafrost roadbed in Qinghai-Tibet Railway is mainly influenced and controlled by cryogenic course. The results obtained from analysis of the course after construction of the railway and the data from in-situ engineering tests have pointed out that there exists an intimate relationship between the deformation of permafrost embankment in different phases and the soil’s cryogenic course. The results also show that if man can control the stabilizing time of the cryogenic course and the ground’s temperature field configuration of the filling roadbed

then the deformation of the roadbed can be reduced during the cryogenic course and the long-term operation course of the railway; thus ensuring the long-term stability of the roadbed project in permafrost regions effectively. This has been proved right in the engineering practice of the construction of Qinghai-Tibet Railway on permafrost soils.