The paper investigates the failure of brittle rocks within a multiscale/multiphysics computational modeling framework so as to explicitly incorporate both microstructural and hydromechanical aspects in their overall (nonlinear) fracture behavior. Herein, the rock is idealized as a microfissured porous medium via a representative elementary volume (REV) containing distributed oblate spheroidal open microcracks and spheroidal nanopores at the lower scales. A two‐scale analytical homogenization procedure is then performed on the REV, assuming a saturated pore space across the scales. The end result is a microstructurally enriched continuum damage‐poroelasticity constitutive model within the generalized Biot's framework that inherits the underlying small‐scale characteristics. A set of damage tensors is derived based on the directional density distribution of microcracks that operate on both the poromechanical and hydraulic properties. Microstructural evolution is modeled following changes in microcrack length, aperture, and number density, including nanoporosity. To this end, a robust localization procedure is used that accurately captures the macroscopic softening due to microcracking events, leading to a nonlinear (but path‐independent) model. To investigate the baseline features of the model, including the salient effects of microcracking on induced anisotropy and deterioration of poroelastic properties, numerical results of material point‐based computations are discussed in detail. Finally, predictions of the current model are validated against experiments on Fontainebleau sandstone.

中文翻译：

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破裂多孔介质的三维多尺度损伤-孔隙弹性模型

本文研究了多尺度/多物理场计算建模框架内的脆性岩石破坏，以便将微观结构和流体力学方面明确纳入其整体（非线性）断裂行为。在此，岩石通过代表性的基本体积（REV）被理想化为微裂隙多孔介质，该基本体积包含较低级别的分布式扁球形球状微裂纹和球形纳米孔。然后在REV上执行两级分析均质化程序，假设跨整个标尺具有饱和的孔隙空间。最终结果是在广义Biot框架内继承了潜在的小规模特征的，富含微观结构的连续损伤-多孔弹性本构模型。基于微裂纹的方向密度分布导出了一组破坏张量，这些裂纹在孔隙力学和水力特性上均起作用。微观结构演化是根据微裂纹长度，孔径和数量密度（包括纳米孔隙）的变化建模的。为此，使用了鲁棒的定位程序，该程序可以准确捕获由于微裂纹事件引起的宏观软化，从而形成非线性（但与路径无关）模型。为了研究模型的基线特征，包括微裂纹对诱导各向异性的显着影响和多孔弹性性能的恶化，将详细讨论基于材料点的计算的数值结果。最后，对照枫丹白露砂岩的实验验证了当前模型的预测。