PERIDYNAMIC SIMULATION OF FRACTURING IN HETEROGENEOUS ROCK BASED ON X-RAY DIFFRACTION AND SCANNING ELECTRON MICROSCOPE TESTS

Abstract

The mechanical properties and fracture behavior of rocks are significantly influenced by their microscopic characteristics. At present, there is a prevalent treatment of rocks as homogeneous materials or an oversimplified assumption of mesoscopic material properties following the Weibull distribution, often overlooking the impact of mineral composition and porosity. This study addresses these limitations by utilizing X-ray diffraction (XRD) and scanning electron microscope (SEM) tests to capture and characterize the microscopic features of rocks, including mineral composition and porosity. Subsequently, a mesoscopic peridynamic (PD) model is developed employing the Knuth-Durstenfeld shuffling algorithm to accurately reflect the real rock microstructure. The efficacy of this method is validated through experiments conducted on sandy mudstone and fine-grained sandstone. Moreover, a parametric analysis is performed, considering variations in porosities and mineral compositions. As porosity increases, numerous small cracks emerge laterally in the model, causing a notable decline in the rock's strength. Rock comprising a single mineral composition typically displays linear failure behavior. Conversely, a rock with a diverse array of minerals tends to exhibit non-linear failure behavior, indicating an increased level of heterogeneity within the material.