A realistic 3D grain-based modeling approach for reproducing the mechanical and failure behavior of brittle granites

Abstract

Exploring cracking behavior from mineral-scale do good help to understand the failure mechanism of rock materials. The present study proposes a realistic three-dimensional grain-based modeling (3D-GBM) method considering the actual distribution, geometry and mesoscopic mechanical properties of different minerals in granite samples. The geometrical characteristic and distribution were captured based on high-precision computed tomography (CT) scanning and polarized microscopy. The mesoscopic mechanical properties were measured using nanoindentation combined with the scanning electron microscope-energy dispersive spectroscopy scanning (SEM-EDS). The results indicate that the established model can realistically reproduce the mechanical and failure behavior of granite subjected to unconfined compression in terms of stress-strain curves, failure mode, crack evolution, and force transmission. Investigating crack propagation at mineral-scale shows that the relative damage degree is greater at weak boundaries (i.e., boundary related to mica) and relatively soft minerals (i.e., mica) than that of strong boundaries (i.e., quartz-quartz and quartz-feldspar) and stiffer minerals (i.e., quartz and feldspar). Grain boundaries and soft mica minerals play an important role in guiding and deflecting the crack propagation path due to the mismatch in elasticity and strength compared with the stiffer and harder minerals (i.e., quartz and feldspar).