Distinct Element Simulations of the Frictional Behavior of Granular Shear Zones

9805270摩根这一建议的重点是发展和修改的数值技术模拟离散力学的颗粒剪切带使用离散元法（DEM）。 研究的目的是研究这些剪切带内的摩擦过程，使用简单的物理实验来校准数值方法。 最近由哈弗福德学院的J. Gollub博士进行的实验揭示了地质剪切带的许多特征：随着滑动速度的增加而稳定的粘滑滑动行为，组合内的前变形事件，以及组合中由于膨胀效应而导致的摩擦对速度的滞后时间依赖性。 私家侦探建议尝试使用DEM模拟重现Gollub的实验结果，并在这样做时校准特定接触定律的数值实现，如力阻尼和颗粒间摩擦。 特别是，她将探讨使用率态摩擦法在颗粒表面实现滑动摩擦，这可能会解释一些与凿填充剪切区的复杂性。 反过来，DEM模拟将被用来突出一些变形的功能，Gollub观察到，脱落的滑移和本地化现象，在粒状材料中发展的进一步光。

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.