Distinct Element Simulations of the Frictional Behavior of Granular Shear Zones

[805270] morgan本提案的重点是发展和改进使用离散元法（DEM）模拟颗粒剪切带离散力学的数值技术。研究的目的是研究这些剪切区内的摩擦过程，使用简单的物理实验来校准数值方法。哈弗福德学院的J. Gollub博士最近进行的实验揭示了地质剪切带的许多特征：粘滑滑动行为随着滑动速度的增加而稳定，组合内的前兆变形事件，以及由于组合中的膨胀效应而导致的摩擦对速度的滞后时间依赖性。P.I.建议尝试使用DEM模拟重现Gollub的实验结果，并在此过程中校准特定接触定律（如力阻尼和颗粒间摩擦）的数值实现。特别是，她将探索使用速率状态摩擦定律来实现颗粒表面的滑动摩擦，这可能解释一些与沟槽填充剪切区相关的复杂性。反过来，DEM模拟将用于突出Gollub观察到的一些变形特征，进一步阐明颗粒材料中的滑动和局部化现象。

9805270MorganThis proposal focuses on the development and modification of numerical techniques for simulating the discrete mechanics of granular shear zones using the distinct element method (DEM). The goal of the research is to study frictional processes within these shear zones using simple, physical experiments to calibrate the numerical methods. Recent experiments conducted by Dr. J. Gollub at Haverford College reveal many characteristics of geologic shear zones: stick-slip sliding behavior that stabilizes with increasing sliding velocity, precorsory deformation events within the assemblage, and a hysteretic time-dependence of friction on velocity attributed to dilation effects in the assemblage. The P.I. proposes to try to reproduce the results of Gollub's experiments using DEM simulations, and in so doing calibrate numerical implementations of specific contact laws such as force damping and interparticle friction. In particular, she will explore the use of rate-state friction laws for implementing sliding friction at particle surfaces, which may explain some of the complexity associated with gouge-filled shear zones. In turn DEM simulations will be used to highlight some of the deformational features that Gollub has observed, shedding further light on the slip and localization phenomena that develop in granular materials.