Quantitative analysis of shear damage characteristics of rock joint surfaces under different normal stresses

Abstract

Based on shear test and 3D contour scanning technology, the morphology and energy characteristics of rock joint surface under different shear loading conditions were investigated, and the fractal dimension theory was used to quantitatively analyze the damage degree of joint surface. The results show that the peak shear stress of the jointed rock sample increases linearly with the increase of normal stress, and the shear displacement-shear stress curve fluctuates slightly due to the snapping failure of the asperities on the joint surface under the high normal stress; With the increase of the normal stress, the shear damage area of the joints surface shows the characteristics of small dot-like, dot-like, block-like and wavy, respectively, and the damage mode gradually changes from shear wear damage to wear-shear compound damage. With the enhancement of normal confinement, the driving energy required for shear damage of rock joints experienced two stages of rapid growth and slow growth, showing an overall logarithmic growth trend; meanwhile, the fractal dimensional degradation value of shear joint surface shows the linear growth characteristics, and the damage degree of joints increases significantly.

Keywords

rock mechanics / joints / 3D scanning / fractal dimension / normal stress