Thermal modeling of heat balance through embankments in permafrost regions

摘要

Permafrost is widely distributed in the northern hemisphere and permafrost degradation underneath transportation infrastructure is on-going due to many factors, such as climate change. The test site, constructed in 2008 along Alaska Highway at Beaver Creek, Yukon, Canada, provides valuable information on the long-term thermal response of permafrost underneath transportation infrastructure, to disturbances induced by constructions and climate change. The temperature data collected can also be used to calibrate thermal models to gain insight into relative effects of different factors on the sensitivity of the ground thermal regime underneath transportation infrastructure to on-going climate change. A finite-element, 2D heat conduction model, taking ice-water phase change into account, was developed based on the Beaver Creek experimental site characteristics and conditions. To increase the accuracy of the model, site-specific parameters, such as soil properties, near surface air temperature, and embankment dimension, were measured and used as input parameters. After calibration of the model, sensitivity analysis of certain input parameters, such as air temperature, embankment thickness and ground temperature, was conducted for different site conditions. The model was used to develop an engineering design chart allowing assessing the heat balance at the interface between embankment and natural ground. The heat balance analysis and the design chart are based on the results of sensitivity analysis and validated using the data from the Tasiujaq airstrip in Northern Quebec, Canada.