Testing Study on Crack Propagation Due to Rheological Fracture in Quasi-Brittle Material Under Compression- Shear or Double Torsional Loading

摘要

In this paper, the crack propagation measurement for rock is made by using constant displacement relax method of double torsion specimens, it has confirmed the presence of creep fracture on a laboratory-scale, and has obtained the three kinds of creep fracture coalescence patterns: wing crack, primary crack and shear crack. The creep fracture is a stable crack growth essential due to the subcritical propagation of rock-like material crack. Based on viscoelastic fracture mechanics, rheological mechanics and energy principle, the corresponding potential functions have been deduced from inner variable, which included the stress intensity factors, wing crack length and duration time, and the creep fracturecriterion, computational model of damage variable effects have been established. The calculation method and theoretical criterion have provided a new and practical tool for studying microscopic mechanism of creep fracture in rock cracks propagation measurement and macro-mechanism of creep fracture in rock engineering.