Synthesis of physical processes of permafrost degradation and geophysical and geomechanical properties of permafrost

Recent permafrost degradation across the high northern latitude regions has impacted the performance of the civil infrastructure. This study summarizes the current state of physical processes of permafrost degradation in a geotechnical context and the properties of permafrost-affected soils critical for evaluating the performance of infrastructures commonly built in the high northern latitude regions. We collected a total of 96 datasets with 3162 data points from 38 journal and conference publications and analyzed the variations of geomechanical and geophysical properties under the effects of permafrost degradation. The datasets represent a range of geomechanical and geophysical properties of permafrost-affected soils with different compositions under different testing conditions. While the data collected are highly scattered, regression analysis shows that most geomechanical and geophysical properties have strong associations with temperature. These associations highlight that ongoing warming can greatly affect the performance of civil infrastructures at high northern latitudes. These properties include elastic moduli, strength parameters, thermal conductivity, heat capacity, unfrozen water content, and hydraulic conductivity. This paper also discusses other factors, such as soil type, soil composition, and confining pressure, which may further complicate the relationships between temperature and the geomechanical and geophysical properties. Through this review, we identify key knowledge gaps and highlight the complex interplay of permafrost degradation, temperature, soil heterogeneity, and soil geomechanical and geophysical properties. Given the scarcity of certain permafrost properties in addition to the complex processes of permafrost degradation in the geotechnical context, there is a need to establish a comprehensive and curated database of permafrost properties. Hence, we encourage broader collaboration and participation by the engineering and scientific communities in this effort.