Abstract: Artificial ground freezing technology is commonly used in tunnel construction in coastal soil regions. The static and dynamic strength characteristics, as well as the elastic modulus of freeze-thaw chloride silty clay, are crucial for predicting thaw settlement and designing the stability of artificial ground freezing technology. Hence, consolidated-undrained triaxial compression tests and cyclic triaxial tests were conducted with varying salt content, freeze-thaw cycles, and temperatures to investigate the static and dynamic strength as well as the elastic modulus in more detail. The results indicated that all static triaxial stress-strain curves and dynamic triaxial backbone curves exhibited strain-hardening behavior. The initial linear stage of the curve was more pronounced in specimens without freeze-thaw. The static strength initially decreased and then increased with rising salt content. A critical salt content of 1% corresponded to the minimum static strength. When the salt content was ≤3%, the dynamic strength showed no significant change. However, it increased significantly to 1.8 times that of other salt content specimens when the salt content reached 4% after undergoing freezing-thawing at −10 ℃. The increase in salt content led to a 1.1−2.0 times increase in the elastic modulus. The elastic modulus can be normalized as E/E_max and described using a hyperbolic model. For specimens with 2% salt content after freeze-thaw cycles, the damage rates of static and dynamic strength were 52%−66% and 69%−78%, respectively. The damage rates of static and dynamic peak elastic modulus were 90% and 81%, respectively. The impact of freezing temperature on static and dynamic strength and elastic modulus was minimal. This research can establish a theoretical foundation for the utilization of artificial ground freezing technology in marine saline formations, as well as for the prediction and control of post-construction thaw settlement to ensure the safe operation of tunnels.

Key words: chloride saline soil, freeze-thaw, salt content, dynamic shear strength, static shear strength, elastic modulus