Fractal Characterization of Crack Patterns in Intact Rocks Under Triaxial Compression

Understanding crack development in rocks under varying confining stresses is critical for assessing rock mass stability in engineering projects, such as tunnels, slopes, and underground storage facilities. This study employs fractal dimension (D) analysis to quantify crack complexity in diabase, ignimbrite, and marble subjected to triaxial compression, with implications for predicting environmental impacts of rock failure. Crack patterns were evaluated using digital image processing and the box-counting method. Results demonstrate that both confining stress and mineralogical composition significantly influence crack morphology and failure modes. Diabase exhibits highly branched cracks (higher D values) due to its interlocking grain texture, while marble produces simpler cracks (lower D values). The cracking behavior of ignimbrite lies between that of marble and diabase, characterized by curved cracks influenced by its weak matrix. Increasing confinement reduces D values, reflecting smoother cracks and transitions from tensile to shear-dominated failure. These findings highlight the utility of fractal analysis in geomechanics, offering quantitative insights into stress-induced damage evolution and its relevance to sustainable engineering applications.