NEESR-CR: Evolutionary Intensity Measures for More Accurate and Informative Liquefaction Hazard Evaluation

该奖项由2009年美国复苏和再投资法案(公法111-5)资助。该奖项是NSF 09-524项目征集“小乔治·E·布朗地震工程模拟(NEES)研究网络(NEESR)”竞赛的结果，包括华盛顿大学(牵头机构)、阿拉斯加大学、费尔班克斯大学(次级奖项)和波特兰大学(次级奖项)。该项目将利用伦斯勒理工学院的NEES设备场地。土壤液化是一种重要的地震危险，在过去的地震中曾对建筑物、桥梁、大坝、码头和生命线造成广泛破坏。它导致建筑物下沉到地下，桥梁和大坝倒塌，掩埋的坦克和管道从地下冒出来。它还在天然和人造地面上造成了毁灭性的山体滑坡，并摧毁了主要的港口设施。1964年阿拉斯加和日本发生大地震后，土壤液化首次引起工程师的注意。工程师们意识到，类似的地震发生在美国人口稠密和工业化程度较高的地区，如洛杉矶、旧金山、西雅图和波特兰地区，可能会导致液化，导致人员死亡，并造成数十亿美元的经济损失。岩土工程师立即开始工作，制定评估液化危害的程序。虽然已经进行了一些有用和重要的改进，但现在使用的基本程序与30-40年前开发的程序相同，尽管对液化过程的理解有了很大提高。在目前的实践中，地震产生的复杂的瞬时地面运动通常由一个点的最大值和运动持续时间的量度来表示。这种基于峰值幅度的参数没有提供地震中液化发生早或晚的信息，这限制了它们在预测液化影响方面的有效性。在这个项目中，将研究使用地面运动强度的演变测量，即在地面运动持续时间内随时间积累的测量，这将允许将缺失的时间维度纳入液化危险评估问题。将研究土壤液化与各种不同的地面运动强度测量方法之间的关系。这项研究将利用离心机模型和单元测试产生大量的实验验证数据，并提供真实的瞬时加载历史。使用这些运动进行的实验将对地面运动强度测量的孔压和永久变形预测能力提供比目前可用的数据类型更严格、更现实的测试。该项目将为液化危险评估程序的制定提供基础，这些程序比目前使用的程序更准确，并提供重要的补充信息。这类程序将改善公共安全，并更有效地利用翻新/补救资源。一个致力于土壤液化的现有教育网站将得到大幅更新和扩展。我们还将与阿拉斯加原住民科学与工程计划、阿拉斯加8-12年级学生夏季研究学院和俄勒冈州科学与工业博物馆等组织互动，将液化问题和这项研究的好处带给那些通常不会接触到它的学生。该项目的数据将被存档，并通过NEES数据库向公众提供。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This award is an outcome of the NSF 09-524 program solicitation ''George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR)'' competition and includes the University of Washington (lead institution), the University of Alaska, Fairbanks (subaward), and the University of Portland (subaward). This project will utilize the NEES equipment site at Rensselaer Polytechnic Institute.Soil liquefaction is an important seismic hazard that has caused extensive damage to buildings, bridges, dams, wharves, and lifelines in past earthquakes. It has caused buildings to sink into the ground, bridges and dams to collapse, and buried tanks and pipelines to pop out of the ground. It has also caused devastating landslides in both natural and man-made ground, and has destroyed major port facilities.Soil liquefaction first sprang to the attention of engineers following large earthquakes in Alaska and Japan in 1964. Engineers realized that similar earthquakes occurring in more heavily populated and industrialized areas of the United States, such as the Los Angeles, San Francisco, Seattle, and Portland areas, could cause liquefaction that would kill people and produce billions of dollars in economic losses. Geotechnical engineers went to work immediately to produce procedures for evaluating liquefaction hazards. While a number of useful and important refinements have been made, the basic procedures used today are the same as those developed 30-40 years ago, despite greatly improved understanding of the liquefaction process.In current practice, the complex, transient ground motion produced by an earthquake is typically represented by a single point "its maximum value" and a measure of the duration of the motion. Such peak-amplitude-based parameters provide no information on whether liquefaction occurs early or late in an earthquake, which limits their effectiveness in predicting the effects of liquefaction. The use of evolutionary measures of ground motion intensity, i.e., measures that build up with time over the duration of a ground motion, which would allow the missing dimension of time to be brought into the liquefaction hazard evaluation problem, will be investigated in this project. The relationship between soil liquefaction and a variety of different measures of ground motion intensity will be investigated. The research will generate a large amount of experimental validation data using centrifuge model and element testing with realistic, transient loading histories. The experiments performed using these motions will provide a much more severe, and realistic, test of the pore pressure and permanent deformation prediction capabilities of ground motion intensity measures than the types of tests for which data is currently available. This project will provide a basis for the development of liquefaction hazard evaluation procedures that are more accurate and that provide important additional information than currently used procedures. Such procedures will lead to improved public safety and the more efficient use of retrofitting/remediation resources. An existing educational website devoted to soil liquefaction will be substantially updated and expanded. We will also interact with organizations such as the Alaska Native Science and Engineering Program, the Alaska Summer Research Academy for grade 8-12 students, and the Oregon Museum of Science and Industry to bring the problem of liquefaction and the benefits of this research to students who would not normally be exposed to it. Data from this project will be archived and made available to the public through the NEES data repository.