A new anisotropic poroelasticity model to describe damage accumulation during cyclic triaxial loading of rock
A new anisotropic poroelasticity model to describe damage accumulation during cyclic triaxial loading of rock
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DOI：
10.1093/gji/ggac062
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发表时间：
2022-02
影响因子：
2.8
通讯作者：
V. Lyakhovsky;I. Panteleev;E. Shalev;John Browning;T. Mitchell;D. Healy;P. Meredith
中科院分区：
文献类型：
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作者：
V. Lyakhovsky;I. Panteleev;E. Shalev;John Browning;T. Mitchell;D. Healy;P. Meredith
随着时间的推移，地壳岩石会经历反复的应力循环。在复杂的构造环境中，应力可能在空间和时间上演化，如火山或活动断裂带，这些岩石不仅可能经历循环加载和卸载，而且还可能经历应力的旋转和/或重新定向。在这种情况下，任何由此产生的裂纹分布都是按顺序形成的，因此可能是高度各向异性的。因此，记录在变形岩石中的地壳构造历史可能包括复杂的应力路径的证据，包括不同的幅度和方向。尽管如此，主应力变化影响各向异性裂纹分布演化的方式仍然受到很少的限制。在这项工作中，我们在前人的非线性各向异性损伤流变学模型的基础上，提出了一个新的考虑各向异性损伤和孔隙度演化耦合的孔弹性流变学模型。新模型具有以前开发的各向异性损伤模型和标量孔弹性损伤模型的主要特征，包括通过单一公式模拟整个屈服曲线的能力。在新模型中，屈服条件是根据应变张量的不变量来定义的，因此新的公式是根据损伤张量和三轴加载条件而定的方向性屈服条件(每个主方向不同的值)。这使我们能够识别每个主应力方向的屈服条件的演变，并符合测量的累积损伤量从以前的加载循环。各向异性损伤和各向异性压实之间的耦合以及与损伤相关的屈服条件与实验获得的应力-应变曲线有合理的拟合。此外，在不同方向的循环加载过程中，模拟的随时间变化的累积损伤与实验观测到的声发射具有很好的相关性。因此，我们能够重现实验中观察到的定向3D Kaiser‘损伤记忆’效应的许多特征。
Crustal rocks undergo repeated cycles of stress over time. In complex tectonic environments where stresses may evolve both spatially and temporally, such as volcanoes or active fault zones, these rocks may experience not only cyclic loading and unloading, but also rotation and/or reorientation of stresses. In such situations, any resulting crack distributions form sequentially and may therefore be highly anisotropic. Thus, the tectonic history of the crust as recorded in deformed rocks may include evidence for complex stress paths, encompassing different magnitudes and orientations. Despite this, the ways in which variations in principal stresses influence the evolution of anisotropic crack distributions remain poorly constrained. In this work, we build on the previous non-linear anisotropic damage rheology model by presenting a newly developed poroelastic rheological model which accounts for both coupled anisotropic damage and porosity evolution. The new model shares the main features of previously developed anisotropic damage and scalar poroelastic damage models, including the ability to simulate the entire yield curve through a single formulation. In the new model, the yield condition is defined in terms of invariants of the strain tensor, and so the new formulation operates with directional yield conditions (different values for each principal direction) depending on the damage tensor and triaxial loading conditions. This allows us to discern evolving yield conditions for each principal stress direction and fit the measured amounts of accumulated damage from previous loading cycles. Coupling between anisotropic damage and anisotropic compaction along with the damage-dependent yield condition produces a reasonable fit to the experimentally obtained stress-strain curves. Furthermore, the simulated time-dependent cumulative damage is well correlated with experimentally observed acoustic emissions during cyclic loading in different directions. As such, we are able to recreate many of the features of the experimentally observed directional 3D Kaiser ‘damage memory’ effect.