Collaborative Proposal: Laboratory Experiments to Understand Dynamic Slip Weakening in Rocks and Analog Materials

合作提案：了解岩石和模拟材料动态滑移弱化的实验室实验

• 批准号: 0810083
• 负责人: Vikas Prakash
• 金额: $ 25万
• 依托单位: Case Western Reserve University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0810083&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Laboratory; Experiments; Understand

In order to determine where best to deploy limited resources for mitigating earthquake loss in the US, we need to understand when and where earthquakes may occur and how intense their accelerations can be. Every time an earthquake occurs, we gain more understanding of the earthquake problem through measurements of ground motion and modeling of seismic sources. In addition to information derived from earthquakes, we can also benefit from improved understanding of the seismic source through laboratory measurements and modeling, to anticipate what may occur in future earthquakes. One of the great gaps in our understanding of source processes is how shear resistance varies on a fault during rapid co-seismic slip and what this implies about the magnitudes of stress drops and near-fault accelerations. In our proposed work plan we will continue our studies on dynamic friction in rocks and analog materials to better understanding thermally-induced slip weakening processes and their consequences for earthquakes, focusing on studies of flash heating/melting at asperity junctions, and fault zone rheological response when there is rapid change in normal stress. We will employ the plate-impact pressure-shear and the modified torsion Kolsky bar experimental configurations. These experimental techniques, developed in our laboratory at CWRU, have been shown by us in pilot experimental studies funded by SCEC, to provide friction data in the slip-speed and normal stress range of relevance to earthquake physics. Besides being useful in the study of dynamic friction at coseismic slip rates, these experimental configurations allow transients, including sudden alterations in both normal stress and shear loading, to be produced to investigate their effects on the fault strength. These studies will be carried out at both room and higher than room test temperatures. The intellectual merit of this proposal is strengthened by the fact that it addresses some of the outstanding problems in earthquake-physics, including the influence of slip, slip velocity, and alterations in normal stress on fault strength during a typical fault rupture process.The broader aspects of our proposal are strengthened by noting that our proposed research will contribute directly towards reducing losses due to earthquakes in the US in a variety of ways. We will acquire data that are essential for creating realistic models of the earthquake process. Moreover, the proposed program provides exciting opportunities for interdisciplinary research and educational interactions. It involves faculty from two universities?Vikas Prakash from Case School of Engineering, CWRU, and David Goldsby from the Department of Geological Sciences at Brown University. The proposed research program will involve one post-doctoral student and undergraduate students at CWRU. These students will receive valuable and unique interdisciplinary exposure to various aspects of earthquake physics, and will benefit from training in diverse areas such as fault mechanics, fracture mechanics, stress wave propagation, experimental diagnostic techniques, and analytical modeling. The available facilities at CWRU represent the state-of-the-art in high-speed friction testing thereby offering the students involved a unique experimental environment. The University is strongly encouraging the involvement of undergraduate students in cutting edge faculty research, and this would occur for the proposed work as well. Special attention will also be given to recruitment of underrepresented minority students for the project. Dissemination of research results is planned by conference presentations and publications in relevant peer-reviewed journals. Topics in the area of earthquake physics and fault mechanics will undoubtedly enter the departmental seminar series. The PIs will also employ internet and mass-media-based information dissemination to increase awareness of the potential impact of the proposed research in earthquake hazard mitigation. This resource will be available to university level and K-12 students as well as the general public.

为了确定在哪里最好地部署有限的资源来减轻美国的地震损失，我们需要了解地震可能发生的时间和地点以及它们的加速度有多强。 每次地震发生时，我们都通过测量地面运动和模拟震源来更多地了解地震问题。 除了从地震中获得的信息外，我们还可以通过实验室测量和建模来更好地了解震源，从而预测未来地震可能发生的情况。 在我们对震源过程的理解中，最大的差距之一是在快速同震滑动期间断层上的剪切阻力如何变化，以及这对应力降和近断层加速度的大小意味着什么。在我们提出的工作计划中，我们将继续研究岩石和模拟材料中的动摩擦，以更好地理解热致滑动弱化过程及其对地震的影响，重点研究粗糙结处的闪速加热/熔融，以及正应力快速变化时断层带的流变响应。 我们将采用板冲击压力剪切和修改的扭转Kolsky杆实验配置。 这些实验技术，在我们的实验室在CWRU开发，已被我们在试点实验研究由SCEC资助，提供摩擦数据的滑动速度和正应力范围内的地震物理学相关。 除了在同震滑动速率的动摩擦研究中是有用的，这些实验配置允许瞬变，包括突然变化的正应力和剪切载荷，要产生调查其对断层强度的影响。这些研究将在室温和高于室温的试验温度下进行。这一建议的智力价值得到了加强，因为它解决了地震物理学中一些突出的问题，包括滑动的影响，滑动速度，在典型的断层破裂过程中，断层强度的正应力和正应力的变化。我们建议的更广泛的方面得到了加强，因为我们注意到，我们提出的研究将直接有助于减少美国地震造成的损失，各种各样的方式。 我们将获得创建地震过程的真实模型所必需的数据。此外，拟议的计划为跨学科研究和教育互动提供了令人兴奋的机会。 它涉及两所大学的教师？CWRU工程学院的Vikas Prakash和布朗大学地质科学系的大卫戈兹比。 拟议的研究计划将涉及一名博士后学生和CWRU的本科生。 这些学生将获得宝贵的和独特的跨学科接触地震物理学的各个方面，并将受益于不同领域的培训，如断层力学，断裂力学，应力波传播，实验诊断技术和分析建模。 CWRU的现有设施代表了高速摩擦测试的最新技术，从而为学生提供了独特的实验环境。 该大学强烈鼓励本科生参与尖端的教师研究，这也将发生在拟议的工作中。 还将特别注意为该项目征聘代表性不足的少数民族学生。 计划通过会议介绍和在相关同行评审期刊上发表文章来传播研究成果。 在地震物理学和断层力学领域的主题无疑将进入部门研讨会系列。 研究所还将利用互联网和大众媒体传播信息，以提高人们对拟议研究在减轻地震灾害方面的潜在影响的认识。 该资源将提供给大学和K-12学生以及公众。