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

• 批准号: 1724915
• 负责人: Brady Cox
• 金额: $ 9.92万
• 依托单位: University of Texas at Austin
• 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=1724915&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Advanced; Site

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.

美国已经有 20 多年没有发生过大规模、破坏性广泛的地震了。 然而，通过观察具有相似抗震设计标准和良好基础设施的国家的大地震影响，地震工程不断取得进展。 新西兰这样的国家拥有严格的建筑规范和与美国类似的基础设施，记录地震的影响为我们提供了最好的学习机会，这些经验教训可以直接转移到我们的国家。 凯库拉 Mw7.8 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人口密度城市中不同类型基础设施的影响，这些基础设施位于不同类型的土壤剖面下，受到各种震动强度的影响。 这些情况为研究场地、盆地和地形效应引起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，这将直接适用于洛杉矶、旧金山、西雅图和盐湖城等美国城市。 紧迫性是必要的，因为 PI 目前可以使用一些关键设施，例如惠灵顿中心港。例如，在他们重建港口后，将不再有通道，并且将失去描述地震后地面特征的机会。 此外，新西兰研究人员正在迅速动员起来，在关键地点开展初步研究。 为了整合资源和专业知识，该项目还需要快速动员。 该项目的最终目标是通过改进抗震设计来提高民用基础设施的弹性、可持续性和可负担性，从而造福整个社会。 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经历，这将有助于平衡他们的技术教育，并使他们了解地震中仍然存在的全球相关问题工程。 简而言之，这项工作的更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影响。该研究计划的智力优点包括加深对以下方面的理解：（1）地面运动地层学，复杂岩土环境中的盆地和地形效应； (2)砾石土的液化响应； (3) 不可液化盖层对液化损害潜力的影响； (4) 建筑物和关键港口基础设施对可液化土壤的响应。 特别令人感兴趣的是在距首都惠灵顿断层破裂 60 公里处的天然和填海土壤地点记录的远高于预期的长周期地面运动。 据推测，谷底上方和下方高度变化的地形导致地层、盆地和地形效应之间复杂的相互作用，从而放大了地面运动。 需要以深剪切波速度 (Vs) 剖面和地形阵列研究的形式进行高级场地表征来研究这些现象。 如果没有这些信息，就不可能对凯库拉地震造成的结构损坏和地面破坏进行观察。 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现场特征描述，在这次相对遥远的地震中度震动（PGA 值为 0.13 - 0.24g）下，该设施发生了令人惊讶的严重液化损坏。此外，还需要记录液化引起的码头和船用起重机损坏横向扩散运动，中心港有罕见的砾石液化事件需要记录 南岛其他重要的地面塌陷地点也应迅速进行特征描述，以添加有价值的、易腐烂的数据美国土壤液化触发和横向扩散经验数据库。 计划在惠灵顿和南岛的关键案例历史站点进行高级站点特征研究，使用以下组合：(1) 用于调查基本站点周期的单站水平与垂直频谱比噪声测量，(2) 组合有源源和环境波场表面波测试，用于开发深 Vs 剖面； (3) 锥入试验，揭示现场地层详细情况； (4) 高分辨率 Vs 和 Vp 剖面的直推跨孔测试。 收集和分析这些数据将有助于更好地了解宝贵的经验教训，这些经验教训可直接应用于改进美国的抗震设计实践。

项目成果

Influence of Site Effects on Observed Ground Motions in the Wellington Region from the Mw 7.8 Kaikōura, New Zealand, Earthquake

新西兰凯库拉 7.8 级地震场地效应对惠灵顿地区观测到的地面运动的影响

• DOI: 10.1785/0120170286
• 发表时间: 2018-03
• 期刊: Bulletin of the Seismological Society of America
• 影响因子: 3
• 作者: Bradley, Brendon A.;Wotherspoon, Liam M.;Kaiser, Anna E.;Cox, Brady R.;Jeong, Seokho
• 通讯作者: Jeong, Seokho