(1. State Key Laboratory of Frozen Soil Engineering，Northwest Institute of Eco-Environmental and Resources，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China；2. University of Chinese Academy of Sciences，Beijing 100049，China)
Abstract：Pile foundations of Chalaping bridge in the basically stable low temperature permafrost region and Huashixia test site in the unstable warm permafrost region along the National Road G214 were selected for study. The influence of the pile foundations on the ground temperature was analyzed based on the measured data of ground temperature around the pile foundations regarding the permafrost table，the freezing and thawing processes. The results show that the relatively high thermal conductivity of the pile foundation material accelerates significantly the heat exchange between the ground and atmosphere，which results in the increase of the annual changing range of the ground temperature. The numerical models were established to investigate the long term influence of pile foundations on ground temperature. Under the assumption that the air temperature will rise 2 ℃ in 50 years，the differences of the depth of permafrost table around the pile foundations and in the natural ground will increase，and the permafrost temperature near the piles will rise significantly. This phenomenon is more obvious in the unstable warm permafrost region.
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2017, Vol. 36 
