CAREER: Damage and Fracture Characteristics of Rocks Under a Broad Spectrum of Strain Rates

职业:广泛应变率下岩石的损伤和断裂特征

基本信息

  • 批准号:
    1351931
  • 负责人:
  • 金额:
    $ 40万
  • 依托单位:
  • 依托单位国家:
    美国
  • 项目类别:
    Continuing Grant
  • 财政年份:
    2014
  • 资助国家:
    美国
  • 起止时间:
    2014-09-01 至 2018-04-30
  • 项目状态:
    已结题

项目摘要

The motions of Earth's enormous tectonic plates are typically measured in millimeters to tens of centimeters per year, seemingly confirming the generally-held view that tectonic processes are slow, and have been throughout Earth?s history. In line with this perspective, most laboratory research focused on rock failure has been limited to experiments utilizing slow loading rates. However, many natural processes that pose significant risk for humans (e.g., earthquakes and extraterrestrial impacts), as well as risks associated with human activities (explosions, mine failures, projectile penetration), occur at rates which are hundreds to thousands of time faster than typically simulated in the laboratory. As a result, little experimental data exists to confirm or calibrate theoretical models explaining the connection between these dramatic events and the pulverized rocks found in fault zones, impact, or explosion sites. Therefore, a combined experimental and field investigation is proposed to study brittle rock failure in both earthquake and impact environments. The mechanical behavior of different rock types at fast loading rates is postulated to depend on the microscopic composition and structure of individual minerals within the rocks. If true, this will allow scientists to better predict the consequences of earthquakes and impact events based on the rock structure in individual areas and furthermore allow engineers to design more effective structures to withstand the pressures in mining, petroleum and military environments. Integrated into this research plan is a partnership with Teach for America (TFA), a national teacher corps of college graduates and professionals who commit to teach for two years and raise student achievement in public schools, to create the TFA Geocorps. The TFA Geocorps will be high-achieving secondary school teachers involved in summer research activities related to the project who will also work with the Principal Investigator to design Geophysics-based thematic curriculum units to teach in their own classrooms. Graduate students supported by this project will supplement their academic training by taking active roles in collaborations with the participating TFA Geocorps teachers. Brittle damage accumulates in the earth?s crust via numerous processes ranging from very slow (fault creep) to very fast (extraterrestrial impact). The strain-rate-dependent micromechanics of brittle damage formation in rocks, particularly under confinement, is poorly constrained, yet it is generally understood that rocks become stronger at higher strain rates, and that above a critical strain-rate threshold, failure in compression transitions from localized damage along discrete fractures to delocalized (distributed) fracture damage (i.e., fragmentation or pulverization). A recent series of studies focused on pulverized rocks in fault damage zones provide evidence that ultra-high strain rates (100/s) associated with rupture tip propagation and/or supershear earthquake rupture are responsible for this pulverization. The transition from discrete fracture to fragmentation depends on confinement (burial depth); and the mechanism, although poorly constrained, is likely controlled by the grain-scale structure of rocks and the dynamics of microcrack propagation. Here it is proposed to characterize the high strain rate inelastic response of rocks by following an integrated field, experimental, and theoretical study focused on the strain rate dependence of fracture toughness, strain rate (and confinement) dependence of compressive strength and damage, and comparison with field observations to determine a microstructural signature of strain rate. The proposed work is expected to calibrate damage mechanics models of high strain-rate rock failure, and to characterize damage zones formed in different strain rate (and confinement) regimes. Expected results should provide a basis for distinguishing strain rate and stress conditions responsible for rock damage based on observing fracture networks and seismic anisotropy. While the focus of this work will be on damage created during earthquakes and impacts, the strength and failure characteristics of rocks under high strain rates are also of fundamental interest in mining, petroleum, and military applications related to blasting, rock burst, underground explosions, and protective design.
地球巨大的构造板的运动通常以毫米为单位至每年数十厘米,似乎证实了一般控制的观点,即构造过程很慢,并且在整个地球的历史中一直存在。 从这个角度来看,大多数以岩石故障为重点的实验室研究仅限于使用缓慢的负载速率进行实验。但是,许多自然过程对人(例如地震和外星人的影响)以及与人类活动相关的风险(爆炸,矿山失败,弹丸渗透)构成重大风险(例如,地震和外星人的影响),以比数百万到数百次的时间发生。通常在实验室模拟。结果,几乎没有实验数据来确认或校准理论模型,从而解释了这些戏剧性事件与在断层区域,撞击或爆炸位点中发现的粉碎岩石之间的联系。因此,提出了一项合并的实验和现场调查,以研究地震和冲击环境中的脆性岩石故障。 假定以快速载荷速率的不同岩石类型的机械行为取决于岩石内各个矿物质的显微镜组成和结构。 如果是真的,这将使科学家能够更好地预测基于各个区域的岩石结构的地震和影响事件的后果,并允许工程师设计更有效的结构,以承受采矿,石油和军事环境中的压力。 整合到该研究计划中是与美国教师教师教师团的合作伙伴关系,该伙伴是大学毕业生和专业人士的全国老师,他们致力于教书两年并提高公立学校的学生成就,以创建TFA Geocorps。 TFA Geocorps将是与该项目有关的夏季研究活动的高成就的中学教师,他们还将与主要研究人员合作,设计基于地质物理学的主题课程单元,以在自己的教室中教书。 该项目支持的研究生将通过与参与的TFA GeoCorps老师合作而积极角色来补充他们的学术培训。 脆弱的损害在地球上积聚在大量的过程中,从非常缓慢(故障蠕变)到非常快(外星撞击)。 岩石中脆性损伤形成的应变率依赖性的微力学,尤其是在限制下,受到限制,但通常可以理解,岩石在较高的应变速率下变得更强壮,并且高于临界应变率阈值高于压缩过渡的失败从沿离散断裂的局部损伤到离域(分布式)断裂损伤(即碎裂或粉碎)。 最近的一系列研究集中在断层损伤区域中的粉状岩石上,这证明了与破裂尖端传播和/或超声刺激和/或超壳式地震破裂相关的超高应变率(100/s)是造成这种粉碎的原因。从离散裂缝到碎片的过渡取决于监禁(埋葬深度);尽管岩石的晶尺度结构和MicroCrack传播的动力学,但这种机制虽然受到限制不佳,但可能受到控制。 在这里,提议通过遵循综合场,实验性和理论研究来表征岩石的高应变速率非弹性反应,该研究的重点是骨折韧性,应变速率(和限制)的应变率依赖性,对抗压强度和损害的依赖性以及比较带有场观测,以确定应变率的微结构特征。 预计拟议的工作将校准高应变率岩石故障的损伤力学模型,并表征以不同的应变率(和约束)状态形成的损伤区域。 预期结果应为分歧应变率和应力条件提供基础,从而基于观察到断裂网络和地震各向异性的岩石损伤。 虽然这项工作的重点将放在地震和影响期间造成的损害上,但高应变率下岩石的强度和失败特征也对采矿,石油和与爆炸,岩石爆发,地下爆炸,地下爆炸,地下爆炸,地下爆炸,地下爆炸,石油和军事应用产生了根本兴趣。和保护设计。

项目成果

期刊论文数量(2)
专著数量(0)
科研奖励数量(0)
会议论文数量(0)
专利数量(0)
Experimental constraints on dynamic fragmentation as a dissipative process during seismic slip
RESEARCH FOCUS: How Dynamic Weakening Makes Faults Stronger: The Role Of Melting In Post-Seismic Healing
研究重点:动态弱化如何使断层更强:融化在震后愈合中的作用
  • DOI:
    10.1130/focus122016.1
  • 发表时间:
    2016
  • 期刊:
  • 影响因子:
    5.8
  • 作者:
    Griffith, W. Ashley
  • 通讯作者:
    Griffith, W. Ashley
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WIlliam Griffith其他文献

WIlliam Griffith的其他文献

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{{ truncateString('WIlliam Griffith', 18)}}的其他基金

Collaborative Research: Moving mountains: timing and emplacement of the Marysvale gravity slide complex
合作研究:移动山脉:马里斯维尔重力滑梯综合体的时间和位置
  • 批准号:
    2113155
  • 财政年份:
    2021
  • 资助金额:
    $ 40万
  • 项目类别:
    Standard Grant
CAREER: Damage and Fracture Characteristics of Rocks Under a Broad Spectrum of Strain Rates
职业:广泛应变率下岩石的损伤和断裂特征
  • 批准号:
    1831126
  • 财政年份:
    2017
  • 资助金额:
    $ 40万
  • 项目类别:
    Continuing Grant
Collaborative Research: Developing a Link between Dynamic Friction and Fracture Mechanics Models of Earthquake Rupture using a New Dynamic Double-direct Shear Apparatus
合作研究:使用新型动态双直剪装置建立地震破裂的动态摩擦和断裂力学模型之间的联系
  • 批准号:
    1215669
  • 财政年份:
    2012
  • 资助金额:
    $ 40万
  • 项目类别:
    Standard Grant
Collaborative Research: Developing a Link between Dynamic Friction and Fracture Mechanics Models of Earthquake Rupture using a New Dynamic Double-direct Shear Apparatus
合作研究:使用新型动态双直剪装置建立地震破裂的动态摩擦和断裂力学模型之间的联系
  • 批准号:
    1321598
  • 财政年份:
    2012
  • 资助金额:
    $ 40万
  • 项目类别:
    Standard Grant

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Modifying fragility fracture healing using a gradient-based mechanotransduction fixation approach
使用基于梯度的力传导固定方法改变脆性骨折愈合
  • 批准号:
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  • 财政年份:
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Modifying fragility fracture healing using a gradient-based mechanotransduction fixation approach
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