Shearing Damage Evolution of Natural Rock Joints with Different Wall Strengths

Understanding the shear damage evolution of natural rock joints is of key importance for the stability of rock slopes and underground tunnels. However, the shear damage evolution of natural joints is difficult to determine due to the ubiquitous features of natural rock joints and the invisibility of the shearing process. In this study, the combined technology of “3D scanning + 3D engraving” is used to produce three types of natural rock joint specimens with identical surface morphology characteristics, and AE monitoring is applied to direct shear tests to reveal the shear damage evolution of natural rock joints. A multi-aspect analysis (including shear damage characteristics, dynamic analysis of failure types, and the maximum percentage of microcrack length in the shearing process) is conducted to recognize the shear damage evolution of natural joints. The results indicate that the shear damage characteristics of natural joints are localized and inhomogeneous, the timing and type of main failure in the shearing process will change when normal stress increases, and the increase in normal stress will first suppress and subsequently promote the maximum percentage of microcrack length. These results will encourage a better understanding of the shear failure mechanism of natural joints and provide references for the precursor identification of shear disasters in geotechnical engineering. Highlights New way of “3D scanning + 3D engraving” is presented to produce a natural rock joint. An improved identification method for failure types and crack length is proposed. Shear damage characteristics of rock joints in the shearing process are exposed.