Mechanical Properties and Damage Model of Transversely Isotropic Rocks Subjected to Freeze-Thaw Cycles

The mechanical properties of bedding rock in cold regions are frequently affected by freeze-thaw (F-T) cycles and anisotropy. Research on the mechanical characteristics of rock damage under the combined action of F-T and bedding angles is limited, and most traditional rock damage models cannot accurately capture these characteristics. We performed axial compression tests to explore the strength characteristics of bedding slates at the bedding angles of β=0°, 30°, 45°, 60°, and 90° under various F-T cycles. The experimental findings suggest that the elastic modulus and uniaxial compressive strength of the slate declined exponentially as the number of F-T cycles increased. Axial compressive strength was characterized by a U-shaped tendency with the bedding angle. This study proposes a damage model for the uniaxial compressive strength of transversely isotropic rock, which integrates the F-T effect, utilizing the enhanced anisotropic Hoek-Brown strength criterion and a statistical damage model. This model was validated using experimental data. This statistical damage model can precisely capture the dual attributes of rock mass strength reduction with F-T cycles and variations arising from the loading direction.