Collaborative Research: An Experimental Study of the Effects of Off-Fault Damage on Earthquake Rupture Mechanics

合作研究：断层损伤对地震破裂力学影响的实验研究

• 批准号: 0711545
• 负责人: Ares Rosakis
• 金额: $ 14.2万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711545&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; Study; Effects

The investigators will extend their laboratory study of the effects of off-fault damage on earthquake rupture propagation from 6x6 inch birefringent polymer plates to 12x12 inch marble plates. For marble, the Rice et al. (2005) model predicts that the interaction of the crack tip with initial damage should extend to distances on the order of 10 cm from the fault plane, in contrast to an interaction distance of about 1 cm in the polymer. The main advantage of using marble is that it has a uniform distribution of 1 mm grains with weak boundaries that can be exploited to produce a uniform millimeter-scale array of initial damage. This combination in marble of a larger damage zone with smaller scale initial damage should allow for the observation of the zone close to the crack tip where models predicts that new damage and granulation should occur.The larger marble plates and nucleation from one edge are also required to keep the rupture from nucleating an out-of-plane tensile wing crack. They have already constructed a larger loading frame and successfully nucleated and propagated mode II shear ruptures on the fault plane in these larger plates. Larger plates are also required to study the larger damage band predicted for marble. The data will be interpreted using the dynamic slip pulse model recently developed by Rice et al. (2005). In this model slip is limited to a finite length of the fault plane, which has the effect of limiting the width of the zone of off-fault damage to a finite value as the rupture speed approaches the limiting Rayleigh speed. The micromechanical model of Ashby and Sammis (1990) will allow the researchers to distinguish between Coulomb slip on preexisting fractures and the generation of new damage, which leads to local failure and the formation of gouge and breccia. The researchers are currently collaborating with Jim Rice and Elizabeth Templeton to cast the Ashby-Sammis damage mechanics into a form that is synergistic with the elastic-perfectly plastic model. The ultimate goal, to model a freely propagating slip pulse in a realistic non-linear medium, remains an unsolved problem. The laboratory experiments proposed here will serve to guide the development of such a model.

研究人员将把断层损伤对地震破裂传播影响的实验室研究从 6x6 英寸双折射聚合物板扩展到 12x12 英寸大理石板。对于大理石，Rice 等人。 (2005) 模型预测裂纹尖端与初始损伤的相互作用应延伸到距断层面约 10 厘米的距离，而聚合物中的相互作用距离约为 1 厘米。使用大理石的主要优点是它具有均匀分布的 1 毫米颗粒和弱边界，可用于产生均匀的毫米级初始损伤阵列。大理石中较大损伤区域与较小规模初始损伤的这种组合应允许观察靠近裂纹尖端的区域，模型预测应在该区域发生新的损伤和粒化。还需要较大的大理石板和从一侧边缘成核以防止断裂形成面外拉伸翼形裂纹。他们已经构建了一个更大的加载框架，并成功地在这些较大板块的断层面上成核并传播了 II 型剪切破裂。还需要更大的板材来研究大理石预测的更大损伤带。这些数据将使用 Rice 等人最近开发的动态滑移脉冲模型进行解释。 （2005）。在该模型中，滑移被限制在断层面的有限长度内，当破裂速度接近极限瑞利速度时，其具有将断层损伤区的宽度限制为有限值的效果。 Ashby 和 Sammis（1990）的微观力学模型将使研究人员能够区分先前存在的裂缝上的库仑滑移和新损伤的产生，后者导致局部破坏以及凿痕和角砾岩的形成。研究人员目前正在与 Jim Rice 和 Elizabeth Templeton 合作，将 Ashby-Sammis 损伤力学转化为与完美弹塑性模型协同的形式。最终目标是在现实的非线性介质中模拟自由传播的滑移脉冲，这仍然是一个未解决的问题。这里提出的实验室实验将有助于指导这种模型的开发。