NEESR-CR: Seismic Earth Pressures on Retaining Structures

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。该奖项是NSF 09-524计划征集“小乔治·E·布朗地震工程模拟(NEES)研究网络(NEESR)”的成果。该奖项包括加州大学伯克利分校(领奖)和加州理工州立大学(分奖)。这项研究利用了加州大学戴维斯分校的NEES土工离心机。智力优势：这项研究的主要目的是推进地震期间作用于挡土结构上的动态力的分析模型。目前使用的方法是从20世纪20年代日本人S所做的工作开始逐渐发展起来的。然而，当时使用的实验方法不能准确地反映结构的真实行为，导致现在的设计建议非常保守，导致设计成本过高。这项研究利用了最先进的实验研究设施，以更好地了解地震期间土壤和挡土结构是如何相互作用的。这项研究建立在最近完成的两个动态离心机实验的基础上，该实验由湾区快速运输(BART)和山谷运输管理局(VTA)资助，以验证他们的设计假设。这项工作的结果表明，目前公认的一些基本假设与观察到的行为不匹配。因此，本研究的目的是通过一系列高质量的土工离心机模型试验来测量嵌岩墙上的动侧向土压力，从而对这一问题进行全面的研究。离心机非常适合于这种建模，因为比例和边界条件允许对土壤行为进行正确的建模，而且离心机模型相对便宜且可重复使用。这项研究还提供了一个重新定义物理试验在发展对土-结构动力相互作用问题的新理解中的作用的机会。物理实验的结果将被用于最新一代的非线性代码，以产生更好的建模和预测能力，并开发适用于基于性能的设计的概率程序。广泛的影响：已经完成的工作已被实践工程师采用，并为BART和VTA节省了大量成本。已经完成的工作的结果还表明，过去对纯分析解决方案和小规模振动台试验的依赖导致了与物理现实无关的代码和设计建议。类似的问题也存在于岩土地震工程的其他方面，需要新的建模和分析方法来产生新的思维和新的解决方案。最终，思维和方法的改变可能会对岩土地震工程的所有领域产生重大影响。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)." This award includes the University of Calfornia, Berkeley (lead), and California Polytechnic State University (subaward). This research utilizes the NEES geotechnical centrifuge at the University of California at Davis.Intellectual Merit: The main objective of this research is to advance the analytical modeling of the dynamic forces acting on earth retaining structures during earthquakes. The methods currently in use have evolved gradually starting with Japanese work performed in the 1920's. However, the experimental methods used at the time were not capable of accurately representing the real behavior of structures and resulted in design recommendations that are now very conservative and that lead to expensive over design. This research takes advantage of the most advanced experimental research facilities to develop a better understanding of how soil and retaining structures interact during earthquakes. The research builds on recently completed series of two dynamic centrifuge experiments funded by the Bay Area Rapid Transit (BART) and the Valley Transportation Authority (VTA) in order to verify their design assumptions. The results of this work show that some of the basic assumptions currently accepted as given do not match the observed behavior. Hence, the purpose of this research is to produce a comprehensive study of the problem by performing a series of high quality geotechnical centrifuge model tests to measure dynamic lateral earth pressures on embedded walls. The centrifuge is ideally suited for this kind of modeling because the scaling and boundary conditions allow for correct modeling of the soil behavior, and centrifuge models are relatively inexpensive and reproducible. This research also presents an opportunity to redefine the role of physical testing in the development of new understanding of dynamic soil-structure interaction problems. The results of the physical experiments will be used in the latest generation of non-linear code to produce better modeling and predictive capabilities and to develop probabilistic procedures suitable for performance based design.Broader Impacts: The work already completed has been adopted by practicing engineers and has resulted in significant cost savings for BART and VTA. The results of the already completed work also show that past reliance on purely analytical solutions and on small scale shaking table tests has resulted in code and design recommendations that have no connection with the physical reality. Similar problems exist in other aspects of geotechnical earthquake engineering and new methods of modeling and analysis are needed to produce fresh thinking and fresh solutions. Ultimately the change in thinking and methodology could have a significant impact in all areas of geotechnical earthquake engineering. Data from this project will be archived and made available to the public through the NEES data repository.