Study on the Influencing Factors of Shear Strength of Carbonate Saline Soil based on Ring Shear Test

The Songnen Plain, situated in the northeastern region of China, is a typical seasonal permafrost zone with extensive carbonate saline soil. Physical parameters and environmental conditions are important factors influencing the mechanical properties of shallow carbonate saline soil. In this study, the effects of dry density (1.35g/cm3, 1.40g/cm3, 1.45g/cm3, 1.50g/cm3), salt content (0.5%, 1.0%, 1.5%), and freeze-thaw cycles (0, 1, 3, 5, 10, 15) on the shear strength of carbonate saline soil were systematically investigated through ring shear tests. The test results conclusively demonstrate that the shear strength of carbonate saline soils exhibits a positive correlation with the dry density. When the dry density increases from 1.35g/cm3 to 1.50g/cm3, the increase range of the shear strength of samples is between 5.0% and 11.3%. The impact on the shear strength of carbonate saline soils is relatively insignificant when the salt content changes in the range of 0.5% to 1.5%, with the shear strength of the soil fluctuating within the range of 1.8% to 3.2%. The freeze-thaw cycles lead to a progressive decay in the shear strength of carbonate saline soils, and the shear strength of the soils attains a relatively stable state after 5 freeze-thaw cycles. After 15 freeze-thaw cycles, the shear strength of carbonate saline soil diminishes by 15.2%. This study can provide scientific references for slope stability analysis and landslide control in regions with carbonate saline soil distribution.