Frost heave modelling of the sunny-shady slope effect with moisture-heat-mechanical coupling considering solar radiation

The sunny-shady slope effect on structures in cold regions is significant due to solar radiation, which threatens structural stability. Solar radiation is rarely considered in modelling frost heave, and its effects on the moisture-heat transfer of frozen soil and structural deformation are unclear. Here, a frost heave model with moisture-heat-mechanical coupling, solar radiation and self-shadowing is presented; its accuracy is verified through comparison with field monitoring data of a canal. Then, the coupling development of the moisture-heat transfer, stress-deformation and differential frost heave progression of differently oriented canals are analyzed. Finally, the effects of solar radiation on the soil frost heave and frost damage mechanism of canals with the sunny-shady slope effect are discussed. The freezing depth is shallower and the water content, deformation, and tensile stress are lower for sunny than for shady slopes. As the canal orientation varies from east-west to north–south, the differences in the freezing characteristics decrease to 0, and the frost damage time of shady slopes is gradually delayed; the opposite occurs for sunny slopes. The developments in structural surface temperature, moisture-heat transfer in frozen soil and structural deformation are consistent with solar radiation and air temperature changes, emphasizing solar radiation’s contribution to structure frost heave. The uneven, asynchronous, asymmetrical frost heave and melting deformation of linings in sunny and shady slopes are the causes of canal damage. This model investigates interactions among solar radiation-diurnal temperature-frozen soil-structures and offers a theoretical basis for using solar energy to reduce frost heave in seasonally frozen regions.