Long-Term Monitoring of Mitigation Techniques of Permafrost Thaw Effects at Tasiujaq Airport in Nunavik, Canada

摘要

This paper summarizes the long-term monitoring (2007-2018) of three test sections in the shoulder of the runway embankment of Tasiujaq Airport. The objective of this test site is to conduct a performance review of-three permafrost protection techniques: gentle slope, air convection embankment (ACE), and heat drain. Each of these techniques and a reference section were installed on the side-slope of the embankment, over a length of 50 m. The results of 10 years of thermal monitoring have shown that the three methods tested have had positive effects on the thermal regime of the ground. While the convective techniques (ACE and heat drain) extracted enough heat from the ground to protect permafrost, the gentle slope was the most effective with a significant decrease in active layer thickness and ground temperature. In Tasiujaq, crosswinds during winter favour snow accumulation along the embankment; the gentle slope is the best option to minimize this effect and to limit the insulation of natural ground. Air convection and heat drain techniques are dependent on the temperature differential between ground and air to initiate convection. Therefore, those techniques are much more effective in regions where the temperature differential is greater.