Regional-scale investigation of pile bearing capacity for Canadian permafrost regions in a warmer climate

Climate change is being experienced particularly intensely in the Arctic and therefore adaptation of engineering systems for this region cannot be further delayed. However, one of the major barriers to studies focused on adapting northern engineering systems is the lack of information at the spatial and temporal scales required for engineering applications. This study investigates pile bearing capacity for selected pile configurations for the Canadian permafrost regions (Nunavut and Northwest Territories), for current and future climates, using the very first ultra-high resolution (4 km) climate change simulation developed for the region using the Global Environmental Multiscale (GEM) model, for a high emission scenario. Comparison of the ultra-high-resolution GEM simulation, driven by reanalysis, with available observations confirms the model's ability in representing near-surface permafrost and related climate variables. The estimated adfreeze contribution to the total bearing capacity, for current climate, informed by the reanalysis-driven GEM simulation, for a 5-m cement pile, is found to be of the order of 15% for regions with shallow bedrock and 80% for regions with deeper bedrock. Application of the GEM climate change simulation outputs, for RCP8.5 scenario, suggest decreases to adfreeze contribution in the 5–30% range by 2040, with the largest differences noted for regions with deeper bedrock. For steel piles of same configuration, although the adfreeze contributions are only about 70% of that for cement piles, the projected relative changes are of similar magnitude. Further downscaling to 250 m resolution using the land model of GEM for the Slave Geological-Grays Bay corridor, where future developments are planned, including an all-season road, enables better estimation of bearing capacity for realistic pile scenarios such as those for bridges (in thick layer of sediments) used for river crossings. Due to the wide variation of pile materials, lengths and installation methods, site specific information can be developed from the framework developed in this study. The results of this study, including the ultra-high resolution climate change information, will thus form the basis for additional detailed investigations on climate-infrastructure interactions and climate resiliency studies.