Effect of Weak‐Filled Layer Properties on the Mechanical Response, Crack Evolution, and Failure Characteristics of Jointed Rock

ABSTRACT Uniaxial compression tests were performed on rock‐like specimens containing a weak‐filled layer (WFL) with a 45° inclination angle and varying joint roughness coefficients (JRC). The results show that increasing JRC causes a tendency to first rise and then decrease in peak stress and to progressively increase in failure strain. The increasing JRC causes the fracture mode transition from interface sliding to mixed tensile–shear failure. A three‐dimensional weak‐filled rough joint (WFRJ) rock‐like numerical model was developed to explore the coupled effects of JRC, filling thickness (T), and strength of WFL ( λ ) using the adaptive solid‐to‐DES method. A higher JRC induces the shift from interface sliding to matrix splitting, while thicker fillings require smaller JRC for the transition and promote broader crack propagation. For low and greater WFL strength, the failure is dominated by interface sliding and matrix splitting, respectively, which means that the higher WFL strength suppresses WFL failure but intensifies matrix damage.