| The permafrost distribution area of China accounts for about10%of the world’s and isthe third largest permafrost superpower in the world. Frozen soil is a kind of specialengineering soil which is mutable and sensitive to temperature. It is formed, developed,extinct and dead by the combined action of crustal inside and outside heat source. Owing tothe special climate, geological condition and interact action with highway engineering, roadconstruction in permafrost region is recognized a serious world problem. Especially since theasphalt pavement is paved, the decrease rate of the permafrost upper limit is increased by theblocking of natural evaporation channel and the heat absorption properties of road surface.With the heating and degradation of permafrost, the road disease occurs serious, roadbeduneven deformation, freeze-thaw damage, waves, longitudinal cracks is happenedoccasionally.The distribution change of water temperature in the permafrost roadbed is the mainfactor that influence the roadbed stability. This paper chooses frozen soil subgrade ofwudaoliang section of the qinghai-tibet highway as the research object, study the frozen soilsubgrade deformation field on the base of the change of temperature field and moisture field,and reveal the deformation distribution and the mechanism of frozen soil subgradedestruction.1. Embankment temperature field in permafrost region is different from generalregion,the infuluence of the soil subgrade inside water phase transition effects on temperaturefield is must be considered, so the phase transformation unsteady temperature field controlequation is to be considered. On the base of the five and a half years measured temperaturedata of K3020+000section in qinghai-tibet highway which is measured by Cold and aridregions environmental and engineering research institute of Chinese academy of sciences, thispaper studys the change rules of temperature field through sets up the permafrost embankmenttemperature field model under the first boundary condition.2. Another important aspect of affecting the stability of frozen soil roadbed is themoisture migration and change, the frost heaving and thaw collapse deformation ofpermafrost subgrade is caused by the changes of moisture migration. So this paper studies on the moisture field change of frozen soil subgrade, and makes basis for study of frozen soilsubgrade deformation field.3. The change of frozen soil roadbed stability is caused by the change of water andtemperature, so study the frost heave deformation during the winter and thawing settlementdeformation under the action of vehicle load and rainy season of wudaoliang section in theqinghai-tibet highway, which is according to the results of the calculation of temperature andmoisture field. Then the damage mechanism of frozen soil roadbed is revealed throughanalysis the subgrade deformation rule.This article research results further reveals the damage mechanism of subgradedeformation which is caused by the water and thermal changes of frozen soil subgrade,provides a certain theoretical basis for prevention and control of qinghai-tibet highwayroadbed diseases and reference significance for the further study of frozen soil subgradestability. |
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