The asymmetric heat-water-deformation responses to solar radiation on sunny and shady slopes cause the failure of water conveyance canals in cold regions, threatening water, food, and ecological security. To investigate the influence of solar radiation on differential heat-water-deformation behaviors, a novel model test equipment incorporating solar radiation and freezing-thawing conditions was developed. A canal model was tested under different solar radiation intensities between slopes during freezing-thawing. Results show that solar radiation intensifies heat flux on the canal surface, increasing temperature while enhancing convective heat loss. Frozen soil phase change leads to solar energy storage in the sunny slope, causing a temperature difference between slopes. This leads to increased disparities in freezing depth, water content, deformation, and strain. Additionally, the disparities in freezing depth, deformation, and strain of both slopes are linearly related to the difference in daily solar radiation absorption. Under a 39.2 W/m2 intensity difference at-15 degrees C ambient temperature, the freezing depth, deformation, and strain of the shady slope can reach 1.4 times those of the sunny slope. Furthermore, the sunny slope has higher surface soil water content, potentially damaging the lining during thawing due to reduced freezing force. These findings enhance our understanding of canal failure mechanisms.

A growing rock engineering activity in cold regions is facing the threat of freeze-thaw (FT) weathering, especially in high mountains where the sunny-shady slope effects strongly control the difference in weathering behavior of rocks. In this paper, an investigation of the degradation of petrophysical characteristics of sandstone specimens subjected to FT cycle tests to simulate the sunny-shady slope effects is presented. To this aim, non-destructive and repeatable testing techniques including weight, ultrasonic waves, and nuclear magnetic resonance methods on standard specimens were performed. For the sunny slope specimens, accompanied by the enlargement of small pores, 100 FT cycles caused a significant decrease in P-wave velocity with an average of 23%, but a consistent rise of 0.18% in mass loss, 34% in porosity, 67% in pore geometrical mean radius, and a remarkable 14.5-fold increase in permeability. However, slight changes with some abnormal trends in physical parameters of the shady slope specimens were observed during FT cycling, which can be attributed to superficial granular disaggregation and pore throat obstruction. Thermal shocks enhance rock weathering on sunny slopes during FT cycles, while FT weathering on shady slopes is restricted to the small pores and the superficial cover. These two factors are primarily responsible for the differences in FT weathering intensity between sunny and shady slopes. The conclusions derived from the interpretation of the experimental results may provide theoretical guidance for the design of slope-failure prevention measures and the selection of transportation routes in cold mountainous regions. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).