Grant: Discovery Grants Program - Individual

Transportation infrastructure is essential for the socio-economic development of Canada's North and for the quality of life of its inhabitants. However, transportation embankments inevitably affect the thermal regime of the permafrost by changing the surface conditions. The magnitude of the damages associated with thaw degradation of the permafrost depends on its thaw sensitivity and its ice content. The conservative design approach is to increase embankment height to keep the permafrost frozen such that the thaw front is contained within thaw stable materials. This approach requires large quantities of quality granular material which is economically and logistically challenging in addition to causing major strain on the environment. This conservative design approach is not always warranted. Indeed, when permafrost that does not contain excess ice, deformations due to thaw consolidation are limited. In such cases, the embankment height can be reduced to minimize the quantity of granular materials used in the construction. The thaw penetration thus exceeds the embankment thickness and stress from traffic loads are transferred to the thawed subgrade. Also, existing infrastructure is affected by climate change such that previously thermally stable embankments can become unstable. A mechanical pavement design methodology is thus required to prevent failure by exceeding the limit values for structural and functional conditions for new and existing infrastructure. The proposed research program aims at the development of engineering tools and methods adapted to climate change for the optimization of the mechanical design for the management of transportation embankments built on a permafrost subgrade. Six (6) graduate students will be trained in this research program as they will gain expertise in permafrost and cold regions geotechnical and transportation engineering. The methodology of the project includes the monitoring of a currently established mechanical test section along the Inuvik-to-Tuktuyatuk highway. The data acquired at the test section will be used to develop and calibrate numerical models to support the development of a design methodology. Laboratory testing of intact and artificial permafrost soils will be performed to characterize the mechanical properties of the permafrost. The results will be used in combination with an existing database of more than 300 thaw consolidation tests to develop relationships for the thaw consolidation behavior coupled with the mechanical properties of thawed permafrost. On a larger scope, the research program will contribute to increasing the understanding of the interaction between infrastructure, permafrost, and climate change.