Mechanics, damage and energy degradation of rock-concrete interfaces exposed to high temperature during cyclic shear

Shear properties of the rock-concrete interface are critical to the stability of deep underground engineering projects, particularly in high-temperature environments caused by geothermal activity, fire or nuclear waste radiation. A series of cyclic shear tests were performed on the pre-heated sandstone-concrete interface under both CNL and CNS conditions. The study carefully examined the degradation characteristics of shear mechanics, as well as the evolution of interfacial damage and energy, during cyclic shear of rock-concrete interface. The experimental results show that the pre-heating temperature and the number of shear cycles have considerable effects on the adhesion, shear strength, normal deformation, shear stiffness and friction coefficient of the sandstone-concrete interface, especially under CNS conditions. Furthermore, the nonlinear evolution of interfacial damage and energy release during cyclic shear is highly dependent on the pre-heating temperature. These test results provide valuable insights for revealing the mechanical degradation and evaluating the shear performance of rock-concrete interfaces in deep underground engineering projects subjected to high-temperature environments.