Speaker
Description
Rock-like materials are widely distributed on Earth and have long attracted attention in geotechnical engineering, particularly in the context of high slopes and deep underground projects. Under complex geological and environmental conditions, rocks often exhibit distinctive mechanical behaviors, such as brittle-ductile transition, inherent and induced anisotropy, and multi-field coupling effects. To characterize such behaviors, numerous macroscopic phenomenological models have been developed over the years. While these models offer advantages in computational efficiency and accuracy, they suffer from limited universality across different geomaterials and poor extrapolation capability beyond their calibrated data ranges.
In this study, we develop a micromechanics-based model within the framework of irreversible thermodynamics and multistep homogenization. Rocks are considered heterogeneous materials composed of a porous matrix and randomly distributed microcracks. The primary energy dissipation mechanisms, such as plastic deformation of the matrix, microcrack propagation, and frictional sliding, are explicitly described and inherently coupled. Through a rigorous two-step homogenization procedure, from micro to meso and from meso to macro, a macroscopic criterion is formulated in terms of the stress field, damage state, and pore pressure. For numerical implementation of the coupled plastic-damage-friction model, a robust and efficient iterative algorithm is proposed within the framework of the return-mapping method. Based on a specific procedure for identifying model parameters, the model is validated by reproducing the mechanical behavior of several quasi-brittle rocks under various loading paths across a wide range of confining pressures and pore pressures. It is found that under low confining pressures, microcrack propagation is the dominant mechanism, while the plastic deformation becomes indispensable under higher confining stresses. The reproduction of varying pore pressure under undrained conditions enables a better description of fluid–solid coupling in rocks. When the matrix is assumed transversely isotropic with respect to bedding orientations, the model is able to account for layered rocks. Furthermore, the model is extended to investigate time-dependent behaviors (i.e., creep and relaxation) by incorporating two fundamental physical mechanisms: viscoplastic deformation of the matrix and sub-critical propagation of microcracks. Both the matrix and microcracks are assumed to evolve toward microstructural equilibrium.
Overall, the predicted results show good agreement with experimental data, and the evolution of different internal variables that have clear physical interpretations can be obtained directly. It is demonstrated that the multiscale model not only provides a consistent framework for capturing the mechanical behavior of rocks but also advances the understanding of underlying mechanisms.
| Country | China |
|---|---|
| Green Housing & Porous Media Focused Abstracts | This abstract is related to Green Housing |
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