The effects of cooling rate and water replenishment conditions on the freezing characteristics of silty clay in seasonal frozen area

Abstract This study aims to investigate the influence of cooling rate and water replenishment on soil frost heave characteristics. A freezing test device was employed to examine the internal temperature variation, freezing deformation, and water migration in silty clay soil samples from the Changchun region. The findings suggest that: The temperature change trend remains consistent across various sampling points in the sample, irrespective of variations in cooling rates and water replenishment. The process can be categorized into four distinct stages: abrupt decline, stable recovery, gradual cooling, and equilibrium. The duration of the three stages, namely sudden drop, stable recovery, and continuous reduction of sample temperature, decreases with an increase in cooling rate under identical water supply conditions, the continuous cooling stage stands out among them. The cooling rate remains consistent, while the duration of temperature decrease, and continuous cooling phase is comparatively prolonged during open water refill conditions. The final temperature inside the sample collected at the same freezing time and temperature point is higher under conditions of open water replenishment compared to closed conditions. The structure of the samples in both open-water supplementation and closed conditions represents a network. Under identical water replenishment conditions, the apparent cold structure width of the samples increases with higher cooling rates. Despite identical water replenishment conditions, the sample exhibits slight variations in vertical frost heave displacement. The magnitude of vertical frost heave displacement increases with a decrease in cooling rate under different water replenishment conditions. The samples experienced moisture migration under both open and closed water replenishment conditions. The moisture content of the soil in the vicinity of the cooling roof exhibits an increase, whereas there is a decrease in the moisture content of the adjacent region. The moisture content at the positive temperature base plate of the sample remains relatively constant under conditions of closed water replenishment.