Investigating dynamic friction using earthquake ruptures produced in the laboratory

利用实验室产生的地震破裂研究动摩擦

基本信息

批准号：
1651235
负责人：
Ares Rosakis
金额：
$ 47万
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：
2017
资助国家：
美国
起止时间：
2017-02-01 至 2020-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1651235&HistoricalAwards=false
关键词：
Investigating dynamic friction using earthquake

项目摘要

This research that will advances fundamental understanding of dynamic friction laws by performing mini-earthquakes in the laboratory. Dynamic friction plays a pivotal role in how earthquake ruptures propagate along pre-existing faults in the Earth's crust, such as the San Andreas Fault in California, and release waves that cause destructive shaking. Yet, the fundamental structure and evolution of dynamic friction is still one of the main uncertainties in earthquake science. The proposed study will enhance our understanding of dynamic friction and hence of earthquake source physics. By improving friction formulations for earthquake-producing faults, this study strives to produce a key ingredient for dynamic rupture simulations and physics-based assessment of seismic hazard.The study will investigate dynamic friction using laboratory experiments, featuring dynamic ruptures spontaneously propagating along a frictional interface. The researchers will employ a digital image correlation technique in combination with high-speed photography to characterize in real time the full-field evolution of displacements, velocities, and stresses, and of friction along rupturing interfaces. The addition of rock gouge&#8232;to the interface of the samples in some experiments will further increase the relevance of the setup to earthquake problems. Furthermore, plans to study friction evolution at locations where a fault meets a free surface and where fault-normal stresses vary rapidly and significantly, will allow tests for recent ideas of shear resistance not being directly proportional to rapid variations in normal stress but rather evolving to such proportionality with slip. The work will also explore the effect of fluids in faulting by conducting&#8232;experiments with fluid injection and studying the regime in which the injection triggers dynamic events. The obtained friction data will help to evaluate and improve the existing dynamic friction formulations by introducing the appropriate new physics in to existing formalisms and by even suggesting new and improved dynamic frictional laws. The inferred friction formulations will be verified by forward simulations of our experimental setup.

这项研究将通过在实验室中进行小型地震来增进对动摩擦定律的基本理解。动摩擦在地震破裂如何沿着地壳中预先存在的断层（例如加利福尼亚州的圣安德烈亚斯断层）传播并释放引起破坏性震动的波方面发挥着关键作用。然而，动摩擦的基本结构和演化仍然是地震科学的主要不确定因素之一。拟议的研究将增强我们对动摩擦的理解，从而增强对震源物理学的理解。通过改进引发地震的断层的摩擦公式，本研究致力于为动态破裂模拟和基于物理的地震危害评估提供关键要素。该研究将利用实验室实验研究动态摩擦，其特点是动态破裂沿着摩擦界面自发传播。研究人员将采用数字图像相关技术与高速摄影相结合，实时表征位移、速度、应力以及沿破裂界面的摩擦的全场演化。在一些实验中，在样品界面添加岩屑将进一步增加该装置与地震问题的相关性。此外，计划研究断层与自由表面相交处以及断层法向应力快速且显着变化的位置处的摩擦演化，这将允许测试最新的抗剪力概念，即抗剪力与法向应力的快速变化不成正比，而是演变为这种与滑差的比例。这项工作还将通过进行流体注入实验并研究注入触发动态事件的方式来探索流体在断层中的影响。通过将适当的新物理引入现有形式体系，甚至提出新的和改进的动态摩擦定律，获得的摩擦数据将有助于评估和改进现有的动态摩擦公式。推断的摩擦公式将通过我们的实验装置的正向模拟进行验证。