Three-Dimensional Mechanical Properties of Salinized Cement-Stabilized Aeolian Sand Under Freeze-Thaw Cycles

In order to investigate the three-dimensional mechanical properties and deterioration mechanisms in aeolian sand stabilized by optimal cement content under freeze-thaw and saline conditions,the cement-improved aeolian sand samples with 0,3% and 5% salt contents were taken as the research object.True triaxial shear tests were performed under different freeze-thaw cycles,intermediate principal stress parameters (b value) and consolidation confining pressures.Using CT technology,three-dimensional pore structures were reconstructed to analyze the stress-strain relationships,shear strength and macro-micro deterioration mechanisms.The results show that freeze-thaw cycles degrade the intergranular cement bonding due to salt expansion and frost heave.As salt content increases,the reduction in shear strength becomes more significant.The three-dimensional pore structures for the specimens with 5% salt content after 0,3,6,and 10 freeze-thaw cycles revealed that the repeated frost heave and water-salt migration resulted in the continuous development in small and medium pores.The porosity increased from 31% to 37%,and the pore connectivity also increased,contributing to the reduction in shear strength after freeze-thaw cycles.Based on the Lade-Duncan strength criterion,the failure parameter k_f decreases as strength deteriorates.Considering the combined effect from freeze-thaw cycles and salt expansion,k_f was used to establish a strength deterioration model to reflect the strength deterioration degree in cement-stabilized aeolian sand under harsh environments and complex stress conditions.This model provides theoretical guidance for the material selection and long-term service performance transportation evaluation infrastructure in desert and saline regions.