Strain localization-controlled rock failure using digital volume correlation technology: In situ compression tests on 3D-printed rock-like samples with a single initial flaw

The study of rock failure mechanisms is fundamental to geotechnical engineering, as it enhances design quality and mitigates disaster risks. This research employed in situ compression tests on 3D-printed rock-like samples with a single flaw, combining Micro-CT scans and a specialized loading device to analyze their behavior. Mechanical properties and failure modes of these printed samples were compared to those of natural flawed sandstones, demonstrating the capability of 3D printing to replicate natural rock characteristics. By reconstructing 3D crack evolution from 2D CT images and applying digital volume correlation (DVC), the study visualized internal strain fields and established a relationship between strain patterns and rock failure. The results reveal that crack initiation consistently occurs at the flaw, advancing into tensile and secondary shear or mixed cracks. For flaw angles ( α ) ranging from 0° to 45°, the 3D-printed samples exhibited a higher number of newly formed cracks and a faster increase in crack volume with strain. In contrast, for flaw angles of 45° ≤ α ≤ 90°, the opposite trend was observed. The internal strain field exhibited significant strain localization, with this uneven distribution playing a critical role in sample failure. When the flaw angle was in the range of 0° ≤ α ≤ 30°, failure was primarily driven by tensile cracks, forming distinct tensile bands. Conversely, for 30° < α ≤ 90°, a combination of tensile and shear cracks dominated the failure, producing both shear and tensile bands in the sample. Additionally, the strain field component ε yy showed a strong correlation with the evolution of internal damage, providing valuable insights into the underlying rock failure mechanisms.