Fracture evolution and anisotropic mechanical properties of layered rock based on discrete element modeling and experimental study

Since numerous geotechnical activities crossing layered rock masses, a comprehensive understanding of their mechanical behavior is crucial for engineering stability assessment. This paper establishes transversely isotropic numerical models with multiple bedding angles using PFC3D. After calibrating the meso-parameters to verify model validity, multi-confining pressure triaxial compression simulations are conducted. The results show that both peak strength and elastic modulus exhibit a “U” shaped with bedding angle increase, divided at 60°; under the same confining pressure, the maximum differences reaching 42.2 % and 26.6 %, respectively; failure characteristics vary significantly with bedding angle, manifesting as axial splitting (0°), shear sliding along bedding planes (30°–60°), and mixed tension-shear failure (90°). The sudden increase in acoustic emission (AE) event count and energy can serve as reliable precursors of rock failure, while the proposed energy competition factor β (ratio of slip energy to bond energy) can effectively characterize rock failure evolution. CT observations indicate that confining pressure suppresses micro-crack initiation and propagation. Tunnel excavation simulations based on discrete element method further demonstrate that bedding angle plays a significant controlling role in surrounding rock deformation patterns and support requirements. The research findings provide important insights for stability assessment and support design in layered rock masses.