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.

With the implementation of China’s western development and “One Belt, One Road” initiative, there are more and more projects in the collapsibility loess area, and the collapsibility loess problem encountered in the construction is becoming more and more prominent. In this paper, the collapsibility loess of the south extension section of Xi’an Metro Line 2 is investigated, and its collapsibility characteristics are studied through a large‐scale site immersion test. The test site was a 15 m diameter circular test pit, which took 35 days for water injection and 60 days for observation after water stopped. The test results showed that the maximum self‐weight collapsibility of the soil layer in the test pit is 32 mm, and the deformation amount is 10.05 mm in Q₃ and 9.55 mm in Q₂. The maximum deformation amount of 32 mm is less than 70 mm in the shallow marker; it may be caused by the paleosol layer as a bridge to provide a support to the overlying soil layer. The shape of the sphere of influence after immersion resembles a trumpet, slightly protruding outwards from the paleosol. The scope of influence between the infiltrated and saturated zones gradually increases with depth, and the saturated zone is generally smaller than the infiltrated zone. The research results of this paper can provide technical support and reference for the construction of Xi’an Metro Line 2 and other related projects in the region.