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.