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Modeling Lithospheric Deformation Using a Compressible Visco-Elasto-Viscoplastic Rheology and the Effective Viscosity Approach
Geochemistry, Geophysics, Geosystems ( IF 4.480 ) Pub Date : 2021-07-09 , DOI: 10.1029/2021gc009675
Thibault Duretz 1, 2 , René Borst 3 , Philippe Yamato 1, 4
Affiliation  

Deformations of the colder regions of the lithosphere mainly occur in the frictional regime. In geodynamic models, frictional plastic deformations are often highly localized (shear bands) and are used as proxies for faults. However, capturing the generation and evolution of shear bands in geodynamic models is troublesome. Indeed, mesh dependency and lack of convergence affect, to some extent, the results of geodynamic models. Here we extend the most common plasticity implementation used in geodynamic codes (effective viscosity approach [EVA]) to include the combined effects of elastic compressibility, plastic dilatancy, strain softening, and viscoplasticity. The latter acts as a regularization that cures most of the known issues of geodynamic models related to frictional plasticity. Using regularized models based on the M2Di MATLAB routines, we show that volumetric elasto-plastic deformations can significantly impact crustal-scale shear banding. We also show that the artificial overstress caused by viscoplasticity can be mitigated by employing power-law models. Furthermore, we demonstrate that plasticity algorithms common in geodynamics (based on the EVA) can be as accurate as those obtained with algorithms typically used in engineering (return mapping with a consistent tangent operator). Finally, we show examples of long-term tectonic deformations using the state-of-the art geodynamic code MDoodz. They indicate that viscoplastic regularization can be used efficiently to obtain reliable simulations in geodynamics.

中文翻译:

使用可压缩粘弹粘塑性流变学和有效粘度方法模拟岩石圈变形

岩石圈较冷区域的变形主要发生在摩擦状态。在地球动力学模型中,摩擦塑性变形通常高度局部化(剪切带)并用作断层的替代物。然而,在地球动力学模型中捕捉剪切带的产生和演化是很麻烦的。事实上,网格依赖和缺乏收敛在一定程度上影响了地球动力学模型的结果。在这里,我们扩展了地球动力学代码中最常见的塑性实现(有效粘度方法 [EVA]),以包括弹性压缩性、塑性剪胀、应变软化和粘塑性的综合影响。后者作为一种正则化,可以解决大多数与摩擦塑性相关的地球动力学模型的已知问题。使用基于 M2Di MATLAB 例程的正则化模型,我们表明,体积弹塑性变形可以显着影响地壳尺度剪切带。我们还表明,可以通过采用幂律模型来减轻由粘塑性引起的人为过应力。此外,我们证明了地球动力学中常见的塑性算法(基于 EVA)可以与使用工程中通常使用的算法(具有一致切线算子的返回映射)获得的算法一样准确。最后,我们使用最先进的地球动力学代码 MDoodz 展示了长期构造变形的例子。他们表明可以有效地使用粘塑性正则化来获得可靠的地球动力学模拟。我们还表明,可以通过采用幂律模型来减轻由粘塑性引起的人为过应力。此外,我们证明了地球动力学中常见的塑性算法(基于 EVA)可以与使用工程中通常使用的算法(具有一致切线算子的返回映射)获得的算法一样准确。最后,我们使用最先进的地球动力学代码 MDoodz 展示了长期构造变形的例子。他们表明可以有效地使用粘塑性正则化来获得可靠的地球动力学模拟。我们还表明,可以通过采用幂律模型来减轻由粘塑性引起的人为过应力。此外,我们证明了地球动力学中常见的塑性算法(基于 EVA)可以与使用工程中通常使用的算法(具有一致切线算子的返回映射)获得的算法一样准确。最后,我们使用最先进的地球动力学代码 MDoodz 展示了长期构造变形的例子。他们表明可以有效地使用粘塑性正则化来获得可靠的地球动力学模拟。最后,我们使用最先进的地球动力学代码 MDoodz 展示了长期构造变形的例子。他们表明可以有效地使用粘塑性正则化来获得可靠的地球动力学模拟。最后,我们使用最先进的地球动力学代码 MDoodz 展示了长期构造变形的例子。他们表明可以有效地使用粘塑性正则化来获得可靠的地球动力学模拟。
更新日期:2021-08-03
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