Experimental Study on Settlement of Embankment over Permafrost along Qinghai-Tibetan Railway

摘要

Based on the field data of ground temperature and roadway settlement observed during the construction of the experimental embankments over permafrost along the Qinghai-Tibetan Railway , this paper discusses the differences of frost process on the roadway surface from that on the natural ground surface, the changes of permafrost table under the roadway embankment, and the peculiarities of roadway settlement. Analyses of the test results show : 1) The differences of the freezing indexes between the roadway surfaces and the natural ground surfaces are less than those of the thawing indexes for all the test sections; 2) Since the measures of permafrost protection were taken, the permafrost tables under the embankments have raised after the roadway was constructed. The minimum is about 0. 4 m and the maximum is 1. 2 m; 3) the settlements of the roadway are mainly from the compression and creep of the ice-rich frozen soils under the original permafrost tables and the maximum has reached 6～8 cm during the first year after the embankments were constructed. Moreover, concerning the processes of roadway settlement, the deformation of the embankments has no obvious trend of attenuation at present. Especially, for the roadway with high embankments, the settlement may reach a remarkable value and much consideration must be given for this problem.