Influence of fine content on the behavior of sandy soils undergoing artificial freezing in triaxial conditions

Artificial ground freezing (AGF) is used to stabilize loose soils and fractured rocks during tunnel and shaft excavation, ensuring temporary ground stabilization and groundwater control. It is particularly relevant for intermediate soils, where the influence of granulometry on freezing is crucial for effective design. However, existing studies often focus on site-specific materials, limiting broader applicability. This research investigates how fine content influences the freezing behavior of intermediate soils. Sandy soils with varying kaolin content (0% to 15%) are tested under different confining pressures representative of AGF applications. A modified triaxial apparatus simulated field conditions, applying radial thermal loading to replicate freezing around a pipe. Results demonstrated a pronounced dependence on kaolin content. Samples with 15% kaolin exhibited significant swelling, whereas soils with lower kaolin content were classified as non-frost-susceptible. Swelling was mitigated by increasing confining pressure. Water drainage was observed during the freezing process, governed by two mechanisms: (1) the expulsion of liquid water from the freezing front as water turned into ice and (2) cryogenic suction, which drew water toward the freezing front. These findings contribute to a more generalized and quantitative understanding of soil behavior with varying fine content under freezing conditions, facilitating the optimization of AGF applications.