Anders Stuhr Jørgensen

Experimentation of Several Mitigation Methods in Tasiujaq Airport to Minimize the Effects Caused by the Melting of Permafrost

Since the beginning of the 1990s an important increase in the mean annual air temperatures has been recorded in Nunavik, Quebec, Canada. This has lead to the degradation of permafrost, which is threatening the stability of airport and road embankments in the region. In the summer of 2007 a test-site was established at Tasiujaq Airport to study the effect of three different mitigations methods: heat drain, air convection embankment, and gentle slope (8:1). The methods were constructed in the shoulder of the runway embankment, each method over a distance of 50 m. In each section thermistors were installed to study the annual variations of the thermal regime inside the different embankments. After one year of monitoring, interesting cooling trends have been observed in the different test-sections and a substantially reduced maximum thaw depth have been registered during the thawing season.

Frost susceptibility of granular subbase materials contaminated by deicing chemicals

The increase in urban population in arctic areas leads to an increased demand for transportation infrastructures, such as roads and airfields, in the regions. This challenges the road constructions in terms of condition, bearing capacity and maintenance. It is believed that deicing agents used on roads and airfields enters the granular subbase materials and thereby makes the soil more frost susceptible. In this project a series of isothermal frost heave tests has been carried out on granular subbase material from the runway at Kuujjuaq Airport, Quebec, Canada. The tests have been carried out in order to determine the frost susceptibility of the material, when it is contaminated by a deicing agent. Two series of three freezing tests with isothermal cooling has been conducted using identical saline gradient added through brine. Two types of cooling ramp, an automatic cooling and a manual cooling, were used in order to determine any influence from the cooling ramp. The tests included settings that allowed the samples additional brine doing freezing. Hence the water and salinity were measured before and after the tests in order to determine the redistribution of water and salinity. The test results does not support the theory, that a saline gradient effectively can replace a thermal gradient and create favorable conditions for frost heave. There was no evidence of ice segregation during the tests. During freezing, heave of maximum 0.02 % was observed, which is however not considered caused by ice segregation but rather a volume increase by fusion caused by a small amount of pore water. The direction of the frost front could not be determined from the collected test results, and no reduction in bearing capacity or increase in frost susceptibility can be derived from the collected data on the granular subbase material.