Mechanical Behavior and Fracture Evolution of Artificial Rock Specimens Within 3D-Printed Fractures

Coal rock is characterized by numerous cracks, which significantly impact its mechanical properties, such as fracture evolution and strength. In this study, various fracture network models were created using three-dimensional (3D) printing technology. Employing rigid adhesive and different proportions of coal powder, coal-like samples with intricate fracture networks were successfully fabricated. To replicate the mechanical properties of natural coal rocks, uniaxial compression tests were conducted to investigate the mechanical characteristics and failure modes of samples with different coal powder ratios. Additionally, the mechanical response of samples with discrete fracture network (DFN) models was evaluated after freezing treatment. Findings revealed that increasing the coal powder content enhanced the strength of the samples, whereas the introduction of the DFN model reduced their compressive strength. Samples containing the DFN model predominantly exhibited longitudinal fractures as their failure mode, contrasting with the shear fractures observed in the solid model samples. Furthermore, under low-temperature conditions, the artificial specimens exhibited a distinct trend, where brittleness increased proportionally with coal powder content, a phenomenon attributed to the influence of AB adhesive. After applying freezing treatment to DFN model coal-like samples, stress–strain curves resembling those of actual coal rocks were observed, along with a slightly reduced compressive strength and a brittle failure mode characterized by oblique shear failure.