Abstract
To investigate the distribution law of the stress intensity factor (SIF) and fracture characteristics of sandstone containing a prefabricated semicircular bend (SCB) crack, static three-point bending tests were conducted on sandstone half-disc specimens containing different prefabricated crack angles (β), and then the strain and displacement fields on the specimen surface during loading were investigated in combination with the digital image correlation (DIC) technique. Meanwhile, the distribution curve of SIF and the change process of SIF with time were calculated using the finite software ANSYS to study the distribution law. The results of the study on the SIF showed that, as β increased, the degree to which the prefabricated crack tip was stretched gradually weakened, and the degree of shearing first increased and then decreased. Meanwhile, when the specimens were in the I/II mixed fracture mode, the SIF fluctuated more in the early stage of loading, and the KI and KII distribution curves gradually stabilized and produced a crossover or displayed a crossover trend in the middle and late stages of loading; the KI distribution curves of the specimens were more easily affected by the change in β. Combining the crack extension process and DIC analysis, it was found that the concentrated load had an attractive effect on the generation of fracture cracks. When the specimen underwent pure type I fracture, the horizontal strain at the prefabricated crack tip was maximum, and the strain and displacement at the left and right ends of the specimen were almost symmetrically distributed; in the case of mixed type I/II fracture, both sides of the specimen fracture crack showed different degrees of relative sliding, and the displacement field showed an asymmetric distribution in general.
Published Version
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