Abstract: The aim of this study is to explore the connection between salt expansion and frost heave in cooling sulfate saline soil. Freezing deformation tests are conducted on sulfate saline soil samples to examine the variations of salt expansion and frost heave of soil under varying water and salt content. The salt expansion and frost heave are controlled by changing the water content and salt content in the freezing process. Freezing temperature is set as the demarcation point identifying between salt expansion and frost heave. Results reveal a duplicate effect between salt expansion and frost heave in the freezing process, i.e. there is no positive correlation between total deformation of samples and crystalline volume. Total deformation obeys the law of the balance of power between salt expansion and frost heave, which means that total deformation reaches the minimum when salt expansion deformation equals frost heave deformation. The curve between total deformation and ratio of salt expansion displays an M-shape. The research findings are of active significance for further understanding the mechanism, building models, and hazard prevention of salt expansion and frost heave.

Key words: sulfate saline soil, salt expansion, frost heave, freezing temperature, freezing deformation test, duplicate effect, law of the balance of power