New Method for Characterizing the Shear Damage of Natural Rock Joint Based on 3D Engraving and 3D Scanning

A lack of joint specimens with the same natural surface morphology has limited detailed experimental study of the shearing performances of joints. In this technical note, we propose a way to batch-produce rock joints with the same natural surfaces by way of three-dimensional (3D) optical scanning of original rock joint specimens to gain their digitally natural geometry and then 3D rigid engraving. We also present a method for characterizing the shear damage of a natural rock joint. Manufacturing practice for sandstone, marble, and granite joints demonstrates its advantages in reliable precision for joint surface geometry and high efficiency for joint fabrication. At the same time, direct shear tests for the manufactured rock joint specimens indicate that the engraved rock joint can provide stable experimental results. Further analysis of microwearing damage to engraved natural rock joints after shear tests show that the wearing damage to natural rock joints under direct shear testing mainly happens at some local zones with high positive dip angles. These production examinations and experimental certifications indicate that our method can overcome the "bottleneck" difficulty in insufficient joint specimens with the same natural surface morphologies for experimental study, and provide a new way to quantitatively assess a joint's shear damage.