Introduction of a Scaling Factor for Fracture Toughness Measurement of Rocks Using the Semi-circular Bend Test

Abstract This article discusses the scale dependence of mode $$\mathrm {I}$$ I fracture toughness rocks measured via semi-circular bend (SCB) test. An extensive set experiments is conducted to scrutinise variations with size for three distinct rock types radii ranging from 25 300 mm. The lengths process zone (FPZ) different sample sizes are using digital image correlation (DIC) technique. A theoretical model also established that relates value size. theorem based on strip-yield estimate length FPZ, and energy release rate concept relate FPZ toughness. does not rely any experimental-based curve-fitting parameter, but only tensile strength type as well at a specific effects predicted by in good agreement experimental data both length. Finally, correction factors introduced various geometrical configurations SCB specimen, which scale-independent material can be estimated results performed small samples.