Fracture evolution of artificial composite rocks containing interface flaws under uniaxial compression

Abstract

Composite rock with interfaces is widely distributed in nature. Its mechanical properties are significantly different from those of a single layer rock, which has become one of the highlighted issues in engineering design and operation. In this study, uniaxial compression tests are performed on rock-like specimens with two dissimilar layers. The evolution process of the apparent strain field of the specimen is analysed by digital image correlation (DIC). Acoustic emission (AE) technology is used to analyse the damage evolution process of specimens based on energy dissipation theory and the damage evolution model. The research results show that with the increase in the interface angle, the peak compressive strength of the specimen decreases slowly first and then decreases rapidly, increasing when reduced to the minimum. When the inclination angle of the specimen interface is 60°, its strength is the lowest. The higher the overall strength of the specimen is, the more obvious the above phenomenon. DIC technology captures the apparent strain field characteristics of each stage of specimen failure, which provides a basis for the analysis of the specimen failure mode. The failure modes of the specimens can be divided into five categories. When the inclination angles of the interface are 0°, 60°, 75° and 90°, the failure modes of the specimens are mainly affected by the inclination angle. When the inclination angles are 15°, 30° and 45°, the failure modes are affected by the inclination angle and the rock matrix strength. The damage evolution process of most specimens is divided into four stages. Some specimens only show three stages, such as those specimens with an interface inclination angle of 60°.