Experimental investigation on the size effects of KIC in selected rock types

Abstract

[Abstract] In this study, two specimen geometries were used to determine the mode-I fracture toughness (KIC) of rock: Semi-Circular Bend (SCB) specimens subjected to three-point bending, and pseudo-Compact Tension (pCT) specimens loaded in pure tension. We discuss the results of a number of tests performed on four different types of rock (Arcera, Pinacas and Corvio sandstones, and Blanco Mera granite), which served as a basis for comparison between both testing methods. In addition, specimens of 100, 50 and 38 mm in diameter were used in order to assess eventual size effects on KIC. The effect of notch length was also analyzed by testing specimens with varying notch length ratios. Our experimental results suggest that both specimen size and notch length have an effect on KIC. KIC was found to be dependent on the specimen geometry and testing method, with pCT specimens yielding more consistent values than SCB specimens.