Main factors influencing artificial upper table for embankment of Qinghai-Tibet railway in permafrost region

The research results based on Qinghai-Tibet railway project and relevant test data indicate that the main factors, which influence the artificial upper table for embankment of Qinghai-Tibet railway in permafrost region, are in turn the temperature, the mean annual ground temperature, the fill type, the embankment height, the slope orientation and wind, and the construction season, etc. The temperature affects the artificial permafrost table through the downward dissemination of embankment surface temperature. The mean annual ground temperature as a cold source underneath is also playing a certain role in it from bottom to top. The coarse-grained soil as embankment fill can meet the basic condition of heat transfer theory to uplift artificial permafrost table. It is a positive correlation between the embankment height and the uplift value of artificial permafrost table in a reasonable range of height. The embankment, which runs from east to west, easily forms an increasing asymmetrical artificial permafrost table, but which runs from north to south, easily forms an increasing symmetrical one. The high temperature interlayer has been formed in basement strata of the embankment constructed during the warm season. It affects the restoration of embankment ground temperature field.