Influence of hole shape on fracture evolution of rock-like specimen under compressive-shear load using DIC method

This study systematically investigated the fracture processes of rock-like specimens containing circular, elliptical, trapezoidal, square, and inverted U-shaped holes under compressive-shear load, utilizing digital image correlation (DIC) technology. High-resolution strain and displacement field data were used to capture the complete evolution of crack initiation, propagation, and coalescence. A novel fracture mechanism evolution index (FMEI) model was proposed to dynamically and quantitatively identify the dominant stress mechanisms throughout the loading process. The results indicated that holes with sharp corners tended to induce severe stress concentrations and early failure, whereas circular and elliptical holes exhibited higher load-bearing capacity and more stable crack paths.Most cracks displayed a mixed shear-tensile (ST) failure mode, with the governing stress type exhibited distinct spatiotemporal transitions during fracture development.The FMEI model addressed the limitations of conventional crack identification methods in terms of continuity and quantification, offering a new theoretical framework for analyzing crack patterns and failure mechanisms in complex stress environments.These findings provided valuable insights for the design and stability assessment of cavity-containing structures in underground engineering.