Modeling of instability in cemented granular materials with an enhanced multiscale model

Micromechanics of cemented granular materials provides a critical perspective for analyzing their complex macroscopic behavior, particularly regarding the progressive degradation of microscopic inter-particle bonds. Different from phenomenological approaches, multiscale modeling offers a powerful framework for linking grain-scale mechanics to macroscopic material responses. Building upon the previously developed two-dimensional H -bond model, this study introduces statistical heterogeneity in inter-particle bond strengths and combines it with previously proposed configurational reactions to describe progressive bond failure and post-breakage mesostructural reconfiguration. By mathematically formulating bonded contact stiffness, progressive bond damage, and the ultimate transition toward purely frictional behavior, the model seamlessly upscales these micro-mechanisms to the representative elementary volume (REV) level via statistical homogenization. The numerical results show that the H -bond model reproduces key qualitative features of the essential macroscopic signatures of cemented granular materials under given loading paths, providing insight into the link between bond degradation and macroscopic response. To extend its applicability to boundary value problems, the proposed framework is implemented as a VUMAT subroutine within Abaqus/Explicit. Leveraging this computational capability to simulate a particular landslide, the analysis demonstrates that progressive bond degradation critically governs the onset of macroscopic instability, successfully capturing complex failure mechanisms. Ultimately, this work establishes a computationally tractable and physically rigorous paradigm for embedding microstructural failure mechanisms into large-scale geotechnical analyses.