FLEXURAL/TENSILE STRENGTH RATIO IN ROCK-LIKE MATERIALS

Abstract

Results are presented and discussed from a testing program to study the flexural strength of a rock-like material. In order to investigate the size effects, experiments were performed using specimens of a medium grained size granite. For geometrically similar beams of different sizes, this paper presents and discusses experimental evidence from interferometric measurements (ESPI) and locations of acoustic emissions (AE) of the damage zone development, at the peak load, in terms of shape and size. The bending strengths are compared with the direct tensile strength obtained with double-edge-notched specimens. The experimental strengths are interpreted with a stress analysis in the critical cross-section that takes into account the influence of the localized region of microcracks arising when peak load is approached.