Evaluation of the influence of freeze-thaw cycles on the joint strength of granite in the Eastern Tibetan Plateau, China.

The freeze-thaw cycles will lead to rock deterioration and pose a significant threat to engineering stability in cold regions. In this study, granite samples collected from the Luanshibao Landslide in the Eastern Tibetan Plateau were subjected to a maximum of 120 freeze-thaw cycles at two temperature paths (- 10-20 °C and - 20-20 °C). The Brazilian test, uniaxial and triaxial compression tests were carried out to evaluate the strength behavior of samples while the scanning electron microscopy tests to investigate microstructural changes. The correlation between strength be-havior and microstructural evolution of samples after freeze-thaw cycles was discussed. Results indicate that the uniaxial compressive strength, elastic modulus, tensile strength, and peak strength of samples decreased nonlinearly with freeze-thaw cycles. Besides, freeze-thaw cycles exhibit more pronounced effect on the strength of samples, compared to the temperature path. Based on the Mohr-Coulomb criterion, a joint strength expression was proposed for the tensile, compressive, and shear strengths of granite, which characterizes the influence of freeze-thaw cycles and strength paths on strength behavior of granite samples. SEM images revealed the freeze-thaw damage to the microstructure of granite and further the deterioration of the mechanical properties. The results of this study can provide a valuable reference for assessing the freeze-thaw strength of granite in the context of construction in highland areas, guiding the development of more resilient engineering practices and informing future research on the long-term durability of materials in extreme climates.