Study on Mechanical Properties and Skeleton Deformation of Aeolian Sand-Modified Saline Soil under Freeze-Thaw Cycles

Most existing studies on freeze-thaw cycles in saline soils employ fully constrained freeze-thaw cycles during experiments. However, this approach fails to account for the impact of freeze-thaw cycles on the volume deformation of saline soils. A new indoor freeze-thaw method was developed to directly observe soil skeleton deformation. Using consolidated drained shear tests and scanning electron microscopy, experimental studies were conducted to investigate the effects of freeze-thaw cycles, salt content, and aeolian sand content on the mechanical and deformation properties of saline soils. The results indicate that the higher the initial salt content, the faster the strength decay rate of the soil under freeze-thaw cycles, and the more significant the deterioration and skeleton deformation. As the proportion of aeolian sand increases, the shear strength first increases and then decreases, peaking at 10% proportion with the best surface integrity in the sample. Freeze-thaw cycles significantly increase soil porosity, altering particle contact from face-to-face to point-to-face contact. Modified Duncan-Chang (DC) and volume change models were established, considering the effects of freeze-thaw cycles, salt content, and confining pressure. These models can reflect the stress-strain relationship and volume change patterns of saline soil under combined freeze-thaw and salt erosion effects through skeleton deformation.