Features of Permafrost Technogenic Transformation in Northern Enisey Region Cities

High variability of permafrost conditions in the Northern Enisey Region leads to the significant instability of geocryological conditions, its high sensitivity to the technogenic impacts. This study evaluates the reaction of permafrost layer features on natural and anthropogenic changes in the regional environment, given the cities of Norilsk and Igarka as examples. In Igarka, permafrost conditions are highly affected by the extremely high snow cover, so frozen layer is patchy and tends to exist where the snow cover is removed during the winter. Here the major reason for deformations of buildings is permafrost aggradation, followed by the intensification of frost heave. Operations employing Principle I of northern construction (using grounds in frozen state and conservation of permafrost during exploitation) is sometimes carried out on thaw or high-temperature frozen ground. Ventilation of basements under such conditions leads to soil temperature decrease and intensive frost heave. Permafrost conditions' dynamics during construction and exploitation are often neglected, thus violating major Federal Building Regulations and leading to negative consequences. In Norilsk, which is characterized by much harsher weather conditions, frozen grounds degradation and foundation subsidence is widespread, due to water and sewage system leakages in basements and corresponding heat fluxes. Other reason of permafrost degradation in basements is usage of soil bedding with high filtration ratio and thus relatively higher heat exchange rates. The research results show strong dependency of permafrost conditions and engineering risks in Northern Enisey Region cities on natural conditions and features of technogenic impact.