Volume changes in soil caused by freeze-thaw cycles can affect the shear performance of the saline soil-geotextile interface. To investigate this issue, the study examined changes in shear strength, deformation characteristics, and failure modes of the saline soil-geotextile interface under different numbers of freeze-thaw cycles. The experimental results indicate that with the increase in freeze-thaw cycles, the shear stiffness of the interface initially increases and then decreases, demonstrating the reduction in elasticity and resistance to deformation caused by freeze-thaw cycles. And the enhancement of normal stress can effectively increase the density of the soil and the adhesion at the interface, thereby improving shear stiffness. Meanwhile, the salt content in the soil also significantly impacts the mechanical properties, with notable changes in the dynamic characteristics of the interface as the salt content varies. Furthermore, after freeze-thaw actions, the soil becomes loose, reduces in integrity, features uneven surfaces, and sees increased internal porosity leading to slip surfaces. Trend analysis from this study provides new insights into the failure mechanisms at the saline soil-geotextile interface.

Using geotextiles to improve saline soil roadbeds has become increasingly widespread. However, salt unavoidably enriches at the saline soil-geotextile interface. Under complex external forces, the mechanical properties of the saline soil geotextile interface are not yet clear. Therefore, this study systematically studied the dynamic shear performance of saline soil geotextile interface under dynamic load under different salt content conditions using three shear forms: cyclic direct shear, monotonic direct shear, and post-cycle direct shear. The main research focuses on the influence of salt content, vertical stress and shear displacement amplitude on interface shear strength, stiffness, damping ratio, vertical displacement and other indicators. The results show that after cyclic shear, the strength of the interface of saline soil decreases, and the phenomenon of plastic softening is obvious. The interface shear strength and stiffness exhibit a non-linear relationship with the increase of salt content. When the salt content is 3 %, the interface shear performance reaches its optimum. Excessive salt content can cause crystalline slippage and weaken interface mechanical properties. Increasing vertical stress or reducing shear displacement amplitude is beneficial for improving interface shear strength and stiffness. The amplitude of shear displacement has the greatest impact on the interface damping ratio. The higher the salt content, the more severe the stress damage to the geotextile, and the more significant the accumulation of interface crystallization. The study revealed the mechanical response law of saline soil geotextile interface under dynamic load.