Freeze-Thaw Cycle Impact on Volumetric and Low-Temperature Shear Behavior of High-Salinity Soils

Abstract

Two high-salinity soils with different types of salts were tested to assess the effects of freeze-thaw (F-T) cycles on their volumetric and low-temperature shear behavior. The testing program, including freeze-thaw cycling and triaxial testing, is described in detail. Experimental results, including volumetric change and low-temperature stress-strain behavior and shear strength parameters are presented, and the causes of changes in shear strength parameters are analyzed. The research results show that soils with a high chloride salt content (≥15%) and a low sulfate salt content (≤0.5%) exhibited very small volumetric contractions, whereas soils with a low chloride-salt content (≤5%) and a high sulfate-salt content (≥1.5%) demonstrated very large volumetric expansion after freeze-thaw cycling. There appears to be a residual state for saline soils, at which the void ratio and the stress-strain behavior remains unchanged with an increasing number of F-T cycles. The residual void ratio and the stress-strain behavior at the residual state are much different from those at the initial state for soils with low chloride-salt content and high sulfate-salt content. The large salt expansion and the drop in the apparent cohesion of the soil with a low chloride-salt content and a high sulfate-salt content after F-T cycling is of concern for engineering purposes. These volumetric change and shear strength parameters have a direct or indirect impact on geotechnical analyses, such as assessments of slope stability and bearing capacity and/or load capacity of shallow and deep foundations in similar saline soils.