Micro and macrostructural investigations on the fracture mechanism of the brittle rocks under compressive loading

This study provides valuable insights into the damage patterns and fracture mechanisms of travertine and marble, two rocks widely utilized for various applications. Given the strong correlation between the fracture mechanisms in rocks and their mineralogical, textural, and microstructural characteristics, a thorough investigation of these rocks using both microstructural and macrostructural analyses under compressive loading is essential. To evaluate crack initiation and propagation, Ultrasonic Testing (UT) was employed. To assess the influence of the inherent properties of these rocks on their fracture mechanisms, the CT scanning method was utilized to analyze crack patterns and their orientations. Thin Section technique was employed to examine the effects of natural heterogeneity and the microstructural characteristics of both rock types. Surface damage tracking, local strain concentrations, and stress distributions were analyzed using the Digital Image Correlation (DIC) technique. Numerical modeling using the Discrete Element Method (DEM) was applied to validate the experimental findings and accurately quantify the number of cracks formed in the specimens. The results indicate that travertine, characterized by higher porosity and significant flaws, initiates cracking at a strain level of approximately 0.39%, whereas marble, due to its more homogeneous structure and pre-existing joints, begins to crack at a higher strain level of around 0.59%. Notably, travertine exhibited heterogeneity in its microstructure, leading to localized fracture zones, while marble demonstrated more uniform crack propagation. By leveraging the combination of these techniques, the study effectively targets gaps in the current research landscape, offering a comprehensive approach to understanding fracture mechanism of brittle rocks.