The Research Of Temperature Field Of Wide Embankment In Permafrost Regions

As the development of expressways in China, high grade roads with wide pavem ents are gradually developed in the permafrost regions. The increase of total heat abso rption area and volumetric heat capacity in wide embankment structure and rise of te mperature in embankment and basal permafrost can lead to the melt of permafrost un der embankment settling diseases as the artificial frozen soil under the ceiling move. Permafrost in Qinghai-Tibet Plateau is sensitive to temperature. The actual application of EPS insulation board, block-rock-embankment and thermal probe performed efficient ly. However, the effect of applications has yet to be studied and discussed for wide e mbankment. Based on the numerical simulation results, this paper analyzed the emban kment temperature field of normal roadbed, insulation board roadbed and insulation bo ard-replacement gravel roadbed. And the main topics of this paper are as follows:First, this paper built the control equation of numerical simulation of embankment temperature field based on the theories of numerical simulation of embankment tempe rature field, model parameter and boundary conditions. The thermophysical parameter o f permafrost and boundary conditions was determined considering the climatic environ ment and characteristics of permafrost in Qinghai-Tibet Plateau.Second, this paper compared the temperature contour map, the curve of temperatu re along the depth over time and the graph of annual maximum thaw depth over time. Then the size effect on embankment temperature field was analyzed and the results s howed that the stability of wide embankment was poor, and it improved when the em bankment was higher.. It proposed that the reasonable filling height of embankment wi thout engineering measures was 4-6m.Third, this paper studied the effect of engineering application of insulation emban kment and proposed that the stability improved of insulation embankment with thicker insulation layer and lower depth. It suggested that the reasonable thickness was 0.15-0.25m and the depth was 0.5-1.0m.Last, this paper studied the effect of engineering application of block-rock-embank ment and recommended the reasonable insulation board, along with the appropriate de pth of replacement gravel, according to the numerical simulation results. It suggested t hat the appropriate thickness was 0.08m-0.10m and the depth was 3-5m.