ARCUS | Arctic Research Consortium of the United States

6th Annual ARCUS Award for Arctic Research Excellence


Submitted by   Anna Forsström
Authors   Anna Forsström
Category   Interdisciplinary Research
Title   Maintaining and Creating Permafrost in Subarctic Regions
Affiliation   Civil and Mining Engineering, Luleå University of Technology, Luleå, Sweden

Abstract

In frozen ground, climatic changes and thermal disturbance may cause thawing and degradation of previously frozen ground. If the ground is refrozen, repeated thawing and freezing may cause heaving, settlement, sloughing and creeping. Foundations may be destroyed in a matter of a few seasons. These problems are most pronounced in permafrost regions but also exist in regions with more moderate climate. To overcome this problem thermosyphons are sometimes used in locales like North America, Canada, Greenland and Russia. By using this technique heat is transferred from the ground to the air at a higher rate than what would be the case for natural freezing only. A frozen bulb is then created in the ground and will increase in size year after year. If the trend of today’s climate change and global warming continues it might, in the future, in some locations cause thaw problems of frozen ground. In the Alps, the problems with slopes that have been frozen and now are thawing because of a milder climate may result in an unstable mass of soil. Other examples are footings and foundations for ski lifts where tendencies of thawed ground also are noticed and correspondingly a weaker soil stratum. Use of thermosyphons is one technique that might help to temporarily solve these problems. In the summer of 1999, a PhD project entitled “Thermosyphons in a subarctic climate”, was started at Luleå University of Technology, Sweden. The aim of the project is to examine the necessary climate relations for thermosyphons to be used in Scandinavia and other parts of the world with a similar sub-arctic climate. Installations of thermosyphons were performed in autumn of 2000 at two sites in northern Sweden. At the installation in Dundret, Gällivare, a ski resort at 68°N, the ground temperature as well as the climatic data will be studied in detail. The second installation is at the university campus area in Luleå, at 66°N, where the air and ground temperatures are measured. Results from the installation in Luleå are presented in this paper. As expected, greater cooling of the ground by the thermosyphon was measured compared to natural soil.