SEM in-situ study on the effect of offset-notch on basalt cracking behavior under three-point bending load

Three-point bending fracture tests of basalt with the different offset-notch locations were carried out by an in-situ observation with scanning electron microscope (SEM). These results indicated that the effects of offset-notch location on the crack initiation and propagation behaviors should be classified, the former is not obvious and the latter is sufficiently obvious. Most SEM images demonstrated that the micro-mechanical damage model can explain the influence of offset-notch location on crack propagation paths under a compressive stress, and especially the shear stress component exists. By means of the adjustment parameter λ , the influence of shear stress component contribution to the cracking criterion can be also estimated.