Three-Dimensional Distinct Element Simulations of Dynamic Process of Fault Gouge Evolution

断层泥演化动态过程三维离散元模拟

• 批准号: 0711558
• 负责人: Julia Morgan
• 金额: $ 14.8万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-15 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711558&HistoricalAwards=false
• 关键词: Three; Dimensional; Distinct; Element; Simulations

Brittle fault zones undergo continual wear of fault surfaces during slip, whichleads to a continuous variation in fault surface roughness and a progressive increase inthe thickness of the fault gouge zone with net slip. The dynamic changes in gouge zonefeatures may affect fault frictional strength, stability, and earthquake characteristics.Although previous field, laboratory, and numerical studies have made significantprogress in investigating the geometrical and physical properties of fault gouge zones andtheir effects on fault zone frictional and mechanical behavior, these results still providelimited understanding of the complete process of gouge zone development under a widerange of geological settings, and how these materials might affect the earthquake cycle.Recent modifications to the Distinct Element Method (DEM), including additionof interparticle bonding and breakage, allows us to model the fracture process of cohesiverocks, and makes it possible to directly observe gouge accumulation and modification,mimicking natural fault zone deformation. 2-D DEM simulations of gouge evolutionhave successfully reproduced many observations in the field and laboratory, yieldinginteresting findings that have not been reported in previous gouge zone studies. Theseinclude stages of gouge zone development and their dependence on shear displacement,normal stress, and rock strength. These encouraging results suggest the feasibility,necessity, and importance of improving numerical models and extending the currentstudies into the future.This proposal describes a program to simulate the dynamic processes of gougezone evolution, focused on constraining the relationships between gouge thickness, grainsize distribution, shear zone strength, and surface roughness. We will use much largerassemblages that will allow a wider range of surface and particles sizes and geometries,and conduct these simulations in parallel on the new Rice Cray XD1 supercomputer.Results of these numerical experiments will help in interpreting observations of morecomplex natural faults, leading to an improved understanding of fault zone processes.The work will support training of a postdoctural associate, undergraduates, and provide enhanced 3D codes of fault gouge evolution to the community. Understanding how fault zonesdeform can help improve understanding of how faults slip and thus earthquake hazards.

脆性故障区域在滑动过程中会持续磨损断层表面，这导致断层表面粗糙度的连续变化，并随着净滑动而逐渐增加断层孔区的厚度。峡谷区域场合的动态变化可能会影响断层摩擦强度，稳定性和地震特征。尽管以前的领域，实验室和数值研究在调查故障区域的几何和物理特性方面已经引起了很大的兴趣可能会影响地震周期。对不同元素方法（DEM）的重新修改，包括添加颗粒间粘结和破裂，使我们能够对粘粘器的断裂过程进行建模，并可以直接观察宫颈堆积和修饰，模仿自然断层区域的变形区域。 Gouge EvolutionHave的2-D DEM模拟成功地重现了现场和实验室中的许多观察结果，从而产生了吸引人的发现，这些发现尚未在先前的Gouge区研究中报道。这些包括岩石区发育的阶段及其对剪切位移，正常应力和岩石强度的依赖。这些令人鼓舞的结果表明，改善数值模型并将当前研究扩展到未来的可行性，必要性和重要性。该提案描述了一项计划，以模拟Gogezone演化的动态过程，集中于限制Guge厚度之间的关系，差异，分布区域强度和表面粗糙度。我们将使用更大的大规模组合，这将允许更广泛的表面和颗粒大小和几何形状，并在新的米饭cray XD1超级计算机上并行进行这些模拟。这些数值实验的回应将有助于解释对莫雷克斯自然缺陷的解释观察，从而增强了对断层区域的培训。过错的尺寸gouge进化到社区。了解故障ZonesDeform如何有助于改善对断层滑动的理解，从而使地震危害。