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Time-dependent deformation: bridging the strain rate gap in brittle rocks.

随时间变化的变形：弥合脆性岩石中的应变率差距。

基本信息

批准号：
NE/G019061/1
负责人：
Ian Main
金额：
$ 5.44万
依托单位：
University of Edinburgh
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FG019061%2F1
关键词：
Time dependent deformation bridging strain

项目摘要

Earthquake rupture and volcanic eruptions are the most spectacular manifestations of dynamic failure of critically-stressed crust. However, these are actually rather rare, discrete events in both space and time. Most of the crust spends most of its time in a highly-stressed but sub-critical state. Furthermore, water is ubiquitous in the crust. It is well-known that water-rock chemical reactions can lead to time-dependent deformation enabling rocks to fail over extended periods of time at stresses far below their short-term failure strength; a phenomenon known as 'sub-critical crack growth'. Quantifying sub-critical crack growth is crucial to unravelling the complexities of the evolution and dynamics of the brittle crust. The presence of cracks allows the crust to store and transport fluids, and even modest changes in crack size, density or linkage can produce major changes in fluid transport properties. Time-dependent rock deformation therefore has both a scientific and a socio-economic impact since it controls the duration and detectability of any precursory phase of important geohazards such as earthquake rupture and volcanic eruptions. Such deformation mechanisms cause compaction and cracking, both of which affect porosity and permeability. The results may therefore also be of relevance in the effective recovery of hydrocarbon and geothermal energy resources, and the integrity of long-term storage facilities for hazardous waste. Our current lack of understanding in this area has recently been highlighted by UNESCO, and 'Understanding Slow Deformation before Dynamic Failure' is one of the two priority areas for study within the Natural Hazards theme of its International Year of Planet Earth. We are therefore seeking funds for an integrated laboratory experiment, deep-sea observatory and quantitative analysis study of time-dependent brittle rock deformation, involving the Rock & Ice Physics Laboratory (RIPL) in the Department of Earth Sciences at University College London (UCL), the School of Geo-Science at Edinburgh University (EdU) and the Italian National Institute of Geophysics and Volcanology (INGV). The aim of the project is to discriminate between competing models of time-dependent rock deformation. That is currently not possible given the range of strain rates achievable in conventional laboratory experiments. Our main objective is therefore to use the deep-sea environment to bridge the strain rate gap between laboratory and crustal strain rates. The project will build on previous collaborative work between the groups, and take advantage of recent developments in experimental methodology (RIPL) and theoretical analysis (EdU), and preliminary results achieved during a deep-sea observatory pilot study funded by NERC, where infrastructural support was provided by INGV. The pilot study was originally proposed as a feasibility study for the current proposal, and achieved positive results. We now have a timely opportunity to build on this earlier collaboration and take advantage of access to a unique, new, multi-million Euro deep-sea observatory facility established by INGV on the bed of the Ionian Sea off the east coast of Sicily.

地震破裂和火山爆发是临界应力地壳动力破坏最壮观的表现。然而，这些实际上是相当罕见的，在空间和时间上都是离散事件。大部分地壳大部分时间处于高应力但亚临界状态。此外，水在地壳中无处不在。众所周知，水-岩石化学反应可导致随时间变化的变形，使岩石在远低于其短期破坏强度的应力下长时间破坏;这种现象称为“亚临界裂纹扩展”。量化亚临界裂纹生长对于解开脆性地壳演化和动力学的复杂性至关重要。裂缝的存在使地壳能够储存和输送流体，即使裂缝大小、密度或连接的微小变化也会导致流体输送特性的重大变化。因此，随时间变化的岩石变形既具有科学影响，也具有社会经济影响，因为它控制着地震破裂和火山爆发等重要地质灾害的任何可观测阶段的持续时间和可探测性。这种变形机制导致压实和开裂，这两者都影响孔隙度和渗透率。因此，研究结果也可能与碳氢化合物和地热能资源的有效回收以及危险废物长期储存设施的完整性有关。联合国教科文组织最近强调了我们目前在这一领域缺乏了解的问题，而“了解动态破坏前的缓慢变形”是其国际行星地球年自然灾害主题中的两个优先研究领域之一。因此，我们正在寻求资金，对随时间变化的脆性岩石变形进行综合实验室实验、深海观测和定量分析研究，参与者包括伦敦大学学院地球科学系岩石和冰物理实验室、爱丁堡大学地球科学学院和意大利国家地球物理和火山学研究所。该项目的目的是区分与时间相关的岩石变形的竞争模型。鉴于传统实验室实验中可实现的应变率范围，目前这是不可能的。因此，我们的主要目标是利用深海环境来弥合实验室和地壳应变率之间的应变率差距。该项目将建立在小组之间以前的合作工作的基础上，并利用实验方法（RIPL）和理论分析（EdU）的最新发展，以及由NERC资助的深海观测台试点研究期间取得的初步成果，其中基础设施支持由INGV提供。试点研究最初是作为本提案的可行性研究提出的，并取得了积极成果。我们现在有一个及时的机会，在这一早期合作的基础上再接再厉，利用INGV在西西里东海岸附近的爱奥尼亚海海床上建立的独特的、新的、价值数百万欧元的深海观测设施。