Seasonal thermal insulation to mitigate climate change impacts on foundations in permafrost regions

摘要

Climate change impact on existing infrastructure built on permafrost is of concern to many engineers and scientists. Some studies predict widespread collapse of the existing infrastructure. Adapting structures in the permafrost region to climate change is an important contemporary issue. In this paper, we analyze impacts of permanent and seasonal thermal insulation on permafrost temperature. An analysis of the available data shows that permanent thermal insulation increases the permafrost temperature when the soil surface is exposed to seasonal air temperature variations and when the mean annual soil surface temperature is below 0 degrees C (32 degrees F). We study the thermal impact of seasonal insulation applied in the spring and removed in the autumn to restrict summer heat flow into the ground. The absence of thermal insulation in winter permits soil cooling. We present the results from two-dimensional thermal analyses of a building in the discontinuous permafrost zone. These results show the effectiveness of seasonal thermal insulation. Summer seasonal thermal insulation on the soil surface in a ventilated crawl space decreases permafrost temperature and can be valuable for increasing foundation integrity in a warming climate. The impact of seasonally installed thermal insulation on permafrost increases as the thawing index increases. Seasonal thermal insulation is especially valuable in the discontinuous permafrost zone, where bearing capacity of shallow foundations and adfreeze strength of frozen soil with piles are sensitive to minor soil temperature changes.