Energy-driven damage evolution and instability in fissure-cavity-contained granite induced by freeze-thaw and multistage increasing-amplitude cyclic (F-T-MSIAC) loads

Rock damage and fracture is energy-driven, the energy conversion characteristics for the pre-flawed rock under static or fatigue loading conditions have been well widely studied. However, energy mechanism of rock containing fissures and hollow hole exposed to coupled freeze-thaw and cyclic loads is not well understood. In this work, damage and fracture evolution of pre-flawed hollow-cylinder granite specimens induced by freeze-thaw and multistage increasing-amplitude cyclic (F-T-MSIAC) loads were investigated using energy analysis. Testing results show that the volumetric deformation of rock is affected by the previous freeze-thaw cycles. Rock volumetric deformation decreases with increasing freeze-thaw cycle. The elastic strain energy and dissipated strain energy both decreases with increasing freeze-thaw cycles. When rocks undergo relatively small freeze-thaw cycles, a large amount of energy is consumed to drive crack propagation and cavity collapse. A coupling damage evolution model considering the freezing-thaw and mechanical damage was proposed. The model fits well to the two-stage and three-stage damage accumulation pattern. Two-dimensional CT images reveal different fracture network morphology and the effect of freeze-thaw weathering on crack coalescence. The results show that rock fracture is easy to occur under high freeze-thaw cycles, and less energy is required to communicate the fissures and hollow hole.

Automated summary

This study investigates the damage and fracture evolution of rock containing fissures and hollow hole under freeze-thaw and cyclic loads. The results show that the volumetric deformation of rock decreases with increasing freeze-thaw cycles, and both elastic strain energy and dissipated strain energy decrease as well. A coupling damage evolution model considering freezing-thaw and mechanical damage is proposed.