A finite difference method for off-fault plasticity throughout the earthquake cycle
A finite difference method for off-fault plasticity throughout the earthquake cycle
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DOI：
10.1016/j.jmps.2017.08.002
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发表时间：
2017-12-01
影响因子：
5.3
通讯作者：
Khosravifar, Arash
中科院分区：
文献类型：
--
作者：
Erickson, Brittany A.;Dunham, Eric M.;Khosravifar, Arash
我们已经开发了一个有效的计算框架，模拟多个地震周期与断层外塑性。该方法是为经典的反平面问题的垂直走滑断层所管辖的速率和状态摩擦，通过辐射阻尼近似捕获的惯性效应。率无关的塑性和粘塑性被认为是，其中应力由Drucker-Prager屈服条件约束。断层外体积离散化使用有限差分和构造载荷施加位移远程侧边界以恒定的速率。时间步进结合了自适应龙格-库塔法与增量求解过程，该过程利用弹塑性切线刚度张量和返回映射算法。通过收敛性检验和与有限元解的比较，验证了解决方案。我们量化粘度，各向同性硬化，凝聚力如何影响的大小和断层范围内的塑性应变，发展超过许多破裂。如果包括硬化，则塑性应变在第一次事件之后饱和，并且在随后的破裂期间的响应是有效弹性的。然而，对于没有硬化的粘塑性，连续破裂继续产生额外的塑性应变。在所有的情况下，同震滑动在浅地下减少滑动积累在地震间加载的深度相比。然而，这种滑移赤字的演变与每个后续事件，是由塑性模型。从粘塑性模型的断层外塑性应变的整合表明，非弹性变形（类似于0.1米每破裂，或类似于10%的构造变形预算）容纳了大量的构造偏移。(C)2017爱思唯尔有限公司版权所有
We have developed an efficient computational framework for simulating multiple earthquake cycles with off-fault plasticity. The method is developed for the classical antiplane problem of a vertical strike-slip fault governed by rate-and-state friction, with inertial effects captured through the radiation-damping approximation. Both rate-independent plasticity and viscoplasticity are considered, where stresses are constrained by a Drucker-Prager yield condition. The off-fault volume is discretized using finite differences and tectonic loading is imposed by displacing the remote side boundaries at a constant rate. Time stepping combines an adaptive Runge-Kutta method with an incremental solution process which makes use of an elastoplastic tangent stiffness tensor and the return-mapping algorithm. Solutions are verified by convergence tests and comparison to a finite element solution. We quantify how viscosity, isotropic hardening, and cohesion affect the magnitude and off-fault extent of plastic strain that develops over many ruptures. If hardening is included, plastic strain saturates after the first event and the response during subsequent ruptures is effectively elastic. For viscoplasticity without hardening, however, successive ruptures continue to generate additional plastic strain. In all cases, coseismic slip in the shallow sub-surface is diminished compared to slip accumulated at depth during inter seismic loading. The evolution of this slip deficit with each subsequent event, however, is dictated by the plasticity model. Integration of the off-fault plastic strain from the viscoplastic model reveals that a significant amount of tectonic offset is accommodated by inelastic deformation (similar to 0.1 m per rupture, or similar to 10% of the tectonic deformation budget). (C) 2017 Elsevier Ltd. All rights reserved.