Thermo-Hydro-Mechanical Evolution and Long-Term Stability of Canal Slopes Under Freeze–Thaw Cycles in Cold Regions

Freeze–thaw cycles frequently cause damage to canal slopes in cold regions, which has become a potential adverse factor leading to slope failure. This study investigates the coupled thermo-hydro-mechanical (THM) behavior and stability evolution of canal slopes under freeze–thaw cycle conditions through integrated physical model tests and numerical simulations. The evolution processes of temperature distribution, maximum frozen depth, unfrozen water content, deformation, and safety factor of canal slopes were evaluated. The results showed that both the maximum frozen depth and deformation increased continuously within a reasonable service life of 20 years. The maximum deformation concentrated in the middle of the slope, and the maximum unfrozen water content on the slope surface decreased by 0.06. The stability of a canal slope is subject to the dual influences of service time and seasonal variations. Overall, the safety factor decreases with the increase in service time. The safety factor is influenced by the degree of slope freezing. Compared to November, the safety factor in March of the following year increases by 0.15. As slope failure initiates at the slope toe, necessary engineering measures must be implemented at the slope toe in the design of canals to maintain slope stability. This research provides data support for frost damage mitigation and stability assessment of canals in cold regions.