Two-parameter fracture analysis of SCB rock specimen under mixed mode loading

The semi-circular bend specimen subjected to three-point bending has received much attention in recent years for measuring the mixed mode I/II fracture resistance of rocks. In this paper, the experimental results reported in literature and obtained from fracture tests using the semi-circular bend specimen are revisited for several different rocks including marble, sandstone, limestone, and mudstone. It is shown that a two-term expression for the near-crack-tip stresses together with a criterion based on a fixed critical tangential stress under mixed mode loading provide very good estimates for the experimental results reported for mixed mode I/II fracture in the investigated rocks.