Please cite this article as: Cicero, S., García, T., Castro, J., Madrazo, V., Andrés, D., Analysis of notch effect on the fracture behaviour of granite and limestone: An ABSTRACT This paper presents the analysis of the notch effect on granite and limestone fracture specimens.The research is based on the results obtained in an experimental programme composed of 84 fracture specimens, combining the two materials and 7 different notch radii varying from 0.15 mm up to 10 mm. The notch effect is analysed through the evolution of the apparent fracture toughness and the application of the Theory of the Critical Distances.The results reveal a significant notch effect in the limestone, whereas the notch effect in the granite is negligible for the range of notch radii analysed. Both observations are justified by the corresponding critical distance of the material.
ACCEPTED MANUSCRIPT3 reduction in the resistant section). Additionally, the terms "sharp" and "blunt" are not absolute, but rather they depend on the material: there are materials that present a clear notch effect (e.g., increase in load-bearing capacity and apparent fracture toughness) for very small notch radii (e.g, Madrazo et al., 2012), and there are others that require a certain notch radius to develop a notch effect (e.g., Cicero et al., 2012). This particular nature of notches has led to a great deal of research work over the last few decades, aiming to provide specific tools for the assessment of notched components, beyond the simple and generally overconservative application of ordinary fracture mechanics. However, the analysis of these phenomena in rocks has been scarce, as detailed in the following section.Moreover, size effects are an important issue in rock fracture mechanics, given that the material behaviour (e.g., fracture toughness, tensile strength) and the notch sensitivity may change with the size of the component being analysed (