Abstract
Heterogeneous shale failure is controlled by the coupled effects of mineralogical heterogeneity and pore-fracture architecture, but their cross-scale influence on damage evolution and brittleness remains difficult to quantify. In this study, high-resolution CT imaging, SEM-EDS mineral mapping, and nanoindentation testing were integrated to construct a microstructure-informed multi-component digital rock model. The actual CT-derived pore geometry and SEM-EDS-informed mineral distribution were incorporated into a PFC-based discrete element model, and phase-specific mechanical properties were assigned according to nanoindentation results. The coupled effects of porosity and stiff-mineral content on contact-force evolution, displacement localization, strength, and stiffness were then investigated. The results show that increasing porosity interrupts continuous force-chain pathways, promotes displacement localization, and reduces both peak strength and elastic modulus. In contrast, increasing stiff-mineral content enhances load-transfer efficiency by forming a mineral-controlled load-bearing framework, while the deformability mismatch between stiff minerals and the soft matrix promotes local stress concentration and deformation incompatibility. Based on the simulation and experimental results, a statistical damage constitutive model was established by incorporating porosity-dependent equivalent strength, multicomponent weighted strength, and equivalent elastic modulus. The predicted peak strength and elastic modulus show good agreement with PFC simulation results and laboratory measurements within the tested range, with relative residuals generally constrained within ±10% for strength and ±8% for stiffness. Furthermore, an energy-based brittleness index was used to characterize the brittle-ductile response under different porosity and mineral-content conditions. This study provides a microstructure-informed framework for linking mineral-pore heterogeneity, damage evolution, and brittleness characterization in heterogeneous shale.
Paper Information：
Wang, Z., Sun, J.-M., Li, W., Geng, Z., Micromechanical damage evolution and brittleness characterization of heterogeneous shale based on multi-component digital rock analysis, Geomechanics for Energy and the Environment. https://doi.org/10.1016/j.gete.2026.100882
