Stress effect & scale effect on shear properties of double saw-tooth rock joint surface

Abstract

Abstract The shear properties of rock joint control the stability of rock and have an important impact on natural disasters such as landslides and debris flow. In order to study the stress effect and scale effect of shear properties of double saw-tooth rock joint, cement mortar is selected as similar material, a series of mix ratio tests are carried out, and the best mix ratio is obtained. Using rock joint integrated mold and joint panel produced by 3D printing technology, several groups of double saw-tooth joint specimens with different saw-tooth heights, saw-tooth widths, and saw-tooth spacings are made. Under multiple levels of normal stress, direct shear tests of different scale specimens are carried out by self-developed multifunctional rock-soil contact damage test system. Results show that the shear failure modes of double saw-tooth rock joint include couple effect of overriding and cutting off, and cutting off effect, which are mainly controlled by the rock joint morphology and normal stress. Peak shear strength increases with the increase of saw-tooth width and spacing, but the change with saw-tooth height is not obvious. Peak shear strength and peak friction angle of the double saw-tooth rock joint have significant characteristics of stress effect and scale effect.