To improve the substandard engineering properties of saline soil in cold regions and to mitigate the environmental pollution caused by conventional calcium-based stabilization materials, ionic soil stabilizer (ISS) along with lime and fly ash are added to saline soil. Triaxial tests and discrete element numerical simulations are employed to investigate the macro-microscopic mechanical properties of the ISS stabilized saline soil in a frozen state. The results demonstrate that adding ISS significantly improves the mechanical properties of lime and fly ash-stabilized saline soil under frozen conditions. The strength of the ISS stabilized soil reaches its peak at an ISS content of 3 %, but further increase in ISS content leads to a decrease in strength. The discrete element method (DEM) indicates that a failure surface forms an angle of approximately 55 degrees degrees to the horizontal plane, with particle displacement symmetrical about the failure surface. The pore structure is significantly influenced by confining pressure during loading, and a quantitative analysis is conducted on the changes in porosity and coordination number. This research offers valuable insights for improving the undesirable engineering properties of saline soil in seasonal frozen regions using ISS and for studying its macro-microscopic mechanical characteristics. Additionally, it contributes to reducing the use of inorganic materials, thereby promoting environmental protection.

Nine solidification approaches utilizing two inorganic materials were employed to mitigate the adverse impact of saline-alkali soil on engineering foundations and address the damage caused by freeze-thaw cycles in the Songnen Plain. The impact of inorganic material content on the shear strength of saline-alkali soil and its resistance to freeze-thaw cycles was examined. Additionally, the effectiveness of the solidification scheme was assessed concisely using the Criteria Importance Though Intercrieria Correlation - VlseKriterijumska Optimizcija I Kaompromisno Resenje (CRITIC-VIKOR) model. The findings demonstrate that both lime and fly ash enhance the shear strength of saline-alkali soil, with lime exhibiting superior effectiveness compared to fly ash. Lime induces strain-softening in the stress-strain curve of the soil. At the same time, fly ash significantly improves its resistance to freeze-thaw damage. The combined addition of lime and fly ash strikes an optimal balance between shear strength and freeze-thaw resistance. Considering mechanical performance, freeze-thaw resistance, and economic factors, scheme VII (12% lime content and 0% fly ash content) was selected based on the CRITICVIKOR model as the foundation for solidifying saline-alkali soil in regions of seasonal frost action.