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RAPID/Collaborative Research: Advanced Site Characterization of Key Ground Motion and Ground Failure Case Histories Resulting from the Mw7.8 Kaikoura, New Zealand, Earthquake

RAPID/协作研究：新西兰凯库拉 Mw7.8 地震造成的关键地震动和地面故障案例历史的高级现场表征

基本信息

批准号：
1724575
负责人：
Russell Green
金额：
$ 3.7万
依托单位：
Virginia Polytechnic Institute and State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-02-01 至 2019-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1724575&HistoricalAwards=false
关键词：
RAPID Collaborative Research Advanced Site

项目摘要

A large and widely-damaging earthquake has not occurred in the U.S. for over 20 years. However, advancements have continued to be made in earthquake engineering by observing the effects of large earthquakes in countries that have similar seismic design standards and well-constructed infrastructure. Documenting the effects of earthquakes in a country like New Zealand, which has rigorous building codes and similar infrastructure to the U.S., provides the greatest opportunities for learning lessons that will be directly transferable to our country. The Mw7.8 Kaikoura earthquake provides a unique opportunity to evaluate in considerable depth the effects of earthquake shaking on diverse types of infrastructure, in cities of different population densities, underlain by various types of soil profiles, subjected to a wide range of shaking intensities. These circumstances provide an invaluable opportunity to study ground shaking amplification caused by site, basin and topographic effects, and cases of liquefaction-induced ground failure, that will be directly applicable to U.S. cities such as Los Angeles, San Francisco, Seattle and Salt Lake City. Urgency is required because the PIs currently have access to some key facilities, such as the CentrePort of Wellington. After they have rebuilt the port, for example, there will no longer be access and the opportunity to characterize the ground as it was immediately after the earthquake will be lost . Moreover, New Zealand researchers are rapidly mobilizing to carry out initial studies at key sites. In order to combine resources and expertise, the project will need to also mobilize quickly. The end-goal of this project is to benefit society at-large through increased resiliency, sustainability and affordability of civil infrastructure via improved seismic design. This work will also serve to strengthen international research collaborations between the U.S. and New Zealand, and will provide U.S. graduate students with rewarding international travel experiences that will serve to balance their technical education and expose them to the globally-connected problems that still exist in earthquake engineering. In short, the broader impacts of this work stretch far beyond the borders of New Zealand and will positively impact seismic hazard practices in the U.S. and abroad.The intellectual merits of the research plan include an improved understanding of: (1) ground motion stratigraphy, basin and topographic effects in complex geotechnical settings; (2) liquefaction response of gravelly soils; (3) the influence of non-liquefiable capping layers on liquefaction damage potential; and (4) the response of buildings and critical port infrastructure on liquefiable soil. Of particular interest are the much-higher-than-expected long period ground motions recorded on natural and reclaimed soil sites 60 km from the fault rupture in the capital city of Wellington. It is hypothesized that highly variable topography, both above and below the valley floor, resulted in complex interactions between stratigraphy, basin and topographic effects, amplifying ground motions. Advanced site characterization is needed in the form of deep shear wave velocity (Vs) profiling and topographic array studies to investigate these phenomena. Without this information, it will be impossible to place observations of structural damage and ground failure caused by the Kaikoura earthquake in context. Wellington is the perfect test bed for this study, because abruptly changing topography allows all of these ground motion effects to be studied on a remarkably small scale of several kilometers. Advanced site characterization is also needed at Wellington's port facility, where surprisingly severe liquefaction damage occurred under moderate shaking (PGA values of 0.13 - 0.24g) from this relatively distant earthquake In addition to documenting the damage to wharves and shipping cranes due to liquefaction-induced lateral spread movements, there are rare incidents of gravel liquefaction to document at CentrePort Other important ground failure sites on the South Island should also be characterized rapidly to add valuable, perishable data to the U.S. soil liquefaction triggering and lateral spreading empirical databases. Advanced site characterization studies are planned at key case history sites in Wellington and the South Island using a combination of: (1) Single-station horizontal-to-vertical spectral ratio noise measurements for investigating fundamental site periods, (2) Combined active-source and ambient-wavefield surface wave testing for developing deep Vs profiles; (3) Cone penetration tests for revealing detailed site stratigraphy; and (4) Direct-push crosshole tests for high-resolution Vs and Vp profiles. Collecting and analyzing these data will help to better understand valuable lessons-learned that are directly transferrable to improved seismic design practices in the U.S.

20多年来，美国从未发生过一场破坏性极大的大地震。然而，通过在具有相似抗震设计标准和良好基础设施的国家观察大地震的影响，地震工程继续取得进展。记录地震对新西兰这样的国家的影响，新西兰拥有严格的建筑规范和类似的基础设施，这为我们提供了最大的机会，学习将直接转移到我们国家的经验教训。Mw7.8 Kaikoura地震提供了一个独特的机会，可以相当深入地评估地震震动对不同类型基础设施的影响，这些城市的人口密度不同，被各种类型的土壤剖面覆盖，受到广泛的震动强度的影响。这些情况为研究场地、盆地和地形效应造成的地面震动放大以及液化引起的地面破坏案例提供了宝贵的机会，这些情况将直接适用于洛杉矶、旧金山、西雅图和盐湖城等美国城市。需要紧急情况，因为私人投资机构目前可以进入一些关键设施，如惠灵顿的中央港口。例如，在他们重建港口后，将不再有通道，也不再有机会像地震后立即那样描述地面的特征。此外，新西兰研究人员正在迅速动员，在关键地点进行初步研究。为了整合资源和专业知识，该项目还需要迅速动员起来。该项目的最终目标是通过改进抗震设计，提高民用基础设施的复原力、可持续性和可负担性，从而造福于整个社会。这项工作还将有助于加强美国和新西兰之间的国际研究合作，并将为美国研究生提供有益的国际旅行体验，这些旅行将有助于平衡他们的技术教育，并使他们接触到地震工程中仍然存在的与全球相关的问题。简而言之，这项工作的广泛影响远远超出了新西兰的边界，并将对美国和国外的地震灾害实践产生积极的影响。研究计划的智力优势包括：(1)复杂岩土环境中的地面运动地层、盆地和地形效应；(2)砾石土的液化响应；(3)不可液化盖层对液化破坏潜力的影响；以及(4)建筑物和关键港口基础设施对可液化土壤的响应。尤其令人感兴趣的是，在距离首都惠灵顿断层破裂60公里的自然和开垦土壤场地上记录到的远高于预期的长期地面运动。据假设，谷底上方和下方的高度可变的地形导致了地层、盆地和地形效应之间的复杂相互作用，放大了地面运动。为了研究这些现象，需要以深剪切波速度(VS)剖面图和地形阵列研究的形式进行高级场地表征。如果没有这些信息，就不可能将凯库拉地震造成的结构破坏和地面破坏的观察放在背景下进行。惠灵顿是这项研究的完美试验台，因为突然变化的地形允许在几公里的小范围内研究所有这些地面运动效应。惠灵顿港口设施也需要先进的场地描述，在这场相对较远的地震中，中等震动(PGA值为0.13-0.24g)下发生了令人惊讶的严重液化破坏。除了记录液化引发的横向扩散运动对码头和航运起重机造成的破坏外，CentrePort还记录了罕见的碎石液化事件，南岛其他重要的地面破坏场地也应迅速表征，以向美国土壤液化触发和横向扩散经验数据库添加有价值的易腐数据。计划在惠灵顿和南岛的关键案例现场进行高级场地特征研究，使用以下组合：(1)单站水平与垂直频谱比噪声测量，以调查基本场地周期；(2)活动源面波和环境波场联合面波测试，以开发深层VS剖面；(3)圆锥渗透测试，以揭示详细的场地地层学；以及(4)直接推进井间测试，以获得高分辨率的VS和Vp剖面。收集和分析这些数据将有助于更好地理解宝贵的经验教训，这些经验教训可以直接应用于美国改进的抗震设计实践。