Effect of Temperature on the Shear Strength of Fine-Grained Permafrost Soils

Abstract

Warming of the climate adversely impacts the permafrost by causing a degradation in the shear strength, especially in regions of discontinuous permafrost. This is triggered by an increase in the temperature of the permafrost resulting in an increase in the unfrozen water content and a weakening of underlying materials. Thus, infrastructure built in such regions will be prone to damage and failure. This study investigates the shear strength of fine-grained soils as a function of temperature. For this purpose, a temperature-controlled direct shear device was developed to conduct direct shear experiments at desired temperatures between −10°C and +4°C. The temperature-controlled direct shear device circulates chilled glycol within the device to prepare specimens with uniformly distributed ice contents at various vertical stresses. The results showed that shear strength decreased with an increase in temperature. This reduction in strength was also dependent on the vertical stress and shearing rate. At low temperatures, the samples were seen exhibiting dilative behavior, while contractive behavior was observed in the samples tested at temperatures greater than −2℃. Finally, the peak shear strength of the soil mass decreased with a decrease in the shearing rate.