Experimental and Numerical Analysis of Mode I Fracture Process of Rock by Semi-Circular Bend Specimen

The semi-circular bend (SCB) specimen is widely used to measure fracture toughness of brittle materials such as rock. In this work, the stress field, fracture process zone (FPZ), and crack propagation velocity of SCB specimen are analyzed during the fracture process of rock specimens. The FPZ of specimen is obtained by experimental and numerical methods under a three-point bend test. The stress concentration zones of specimen present a heart shape at peak load points. FPZ forms before macro fracture occurs. The macro fracture form inside FPZ in a post-peak region of a load-displacement curve. The crack propagation process of specimen include two stages, namely the rapid crack initial development stage, and the final crack splitting stage. The maximum crack propagation velocity of specimen is about 267 m/s, and the average crack propagation velocity is about 111 m/s.

Automated summary

The stress field, fracture process zone (FPZ), and crack propagation velocity of SCB specimen during the fracture process of rock specimens were analyzed using experimental and numerical methods. The heart-shaped stress concentration zones formed near the peak load points are identified as FPZ, which forms before macro fracture occurs. The crack propagation process includes two stages: rapid crack initial development stage and final crack splitting stage.