Study on mechanical and fracture characteristics of inclined weak-filled rough joint rock-like specimens

Abstract

Weak-filled rough joint (WFRJ) strongly influence the mechanical and fracture properties of the rock mass. A uniaxial compression test with acoustic emission (AE) and digital image correlation (DIC) system was first conducted on the WFRJ rock-like specimens with a fixed inclination and filling thickness. The test results showed that the increasing JRC of WFRJ caused an increase and then a decrease in peak stress (σp), a steady increase in failure strain (εf) and a steady decrease in elastic modulus (E). And the increasing roughness of WFRJ changes the fracture pattern from sliding fracture along the hard-weak interface to mixed tensile-shear fracture. The AE results demonstrate that the increasing roughness in WFRJ caused the quantity increase in total cracks and the percentage decrease in shear cracks. Then, mechanical models considering local roughness and global structure of the weak filling layer were established to analyze the force characteristic of WFRJ rock-like specimens. Finally, ANSYS/LS-DYNA was used to numerical study the roughness effect of WFRJ specimens. The stress evolution in numerical results is consistent with the X-direction strain field evolution in DIC results. And the quantity and percentage variation laws of cracks in each part were verified by the numerical study results.