CGRG Bibliography of Canadian Geomorphology
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Author : Beaulac, I.; Doré, G.; Allard, M.; and Bourque, A.
Date : 2004.
Title : Permafrost thawing impacts on roads and airfields in Nunavik problem assessment and review of possible solutions.
Publication : Arctic Net. First Annual Scientific Meeting, Palace Royal, Quebec City. December 5-8, 2004. Program.
Issue :
Page(s) : 6.
Abstract
Accelerated degradations of road and airport infrastructures have been observed by the Ministry of Transportation of Québec (MTQ) in some communities of Nunavik. These degradations can make the runways unsafe and force the MTQ to reexamine the maintenance planning. The main objective of the project is to identify realistic scenarios for the adaptation of the transportation infrastructures to the climatic changes prevailing in Nunavik. In this context, this research proposes a review of technical and operational solutions to the problem in order to recommend realistic adaptation scenarios that will assure safe transportation services to the infrastructure users. The main thermal impact on roadways or airfields in the discontinuous permafrost zone after their construction is the increase of the heat flow into embankment during summer that is not compensated by heat extraction from the embankment in winter. Taliks form particularly at the toe of embankment slopes where permafrost is vulnerable due to the low thickness of embankment material, solar radiation in summer and thick snow accumulation in winter (Esch, 1996). Since the 1960’s, many solutions have been proposed and tested to counter the permafrost thawing effects. Some of them have been developed and tested by Alaska Department of Transportation and Public Facilities. Several have been rejected for different reasons and others are still used in construction. The solutions can be classified in three categories: limiting heat intake underneath the embankment, increasing heat extraction from the embankment and reinforcing the embankment in order to resist permafrost degradation problems. Each method will be described and discussed briefly based on different factors such as permafrost context, operation and maintenance, cost, material and equipment availability as well as safety issues. After the field work realized during summer 2004, several indications, such as deflection, settlement, depression, erosion and formation of cracks, confirm the degradation of permafrost under the runways and the access roads. A review of the relevant information was carried out using original geotechnical studies, plans and specifications, airport inspection surveys, degradation surveys and drilling. In addition, it will be possible with land surveying and base material thickness observations to make comparisons between the original and current runway surface profiles in order to evaluate the embankments structure since their construction. Based on the actual information, some adaptation solutions are reviewed in order to reduce permafrost degradation problems of the transportation infrastructures. Constant maintenance, pre-thawing, air convective embankment and air ducts seem to be the best solutions according to the previous enumerated factors. Their performance can be increased if used in combination with thermal insulation and geotextile. Additional solutions such as ventilated embankments with parallel culverts and hard light-colored aggregate surfaces could become feasible, if more further developed.
Bibliography of Canadian Geomorphology