NEESR-CR: Topographic Effects in Strong Ground Motion - From Physical and Numerical Modeling to Design

这个奖项是一个结果的NSF 09-524计划征求“乔治E。小布朗地震工程模拟网络（NEES）研究（NEESR）”竞赛，包括华盛顿州立大学（牵头机构）、德雷克塞尔大学（副奖）、格鲁吉亚理工学院（副奖）、阿肯色州大学（副奖）和马亚圭斯的波多黎各大学（副奖）。该项目将利用位于加州大学戴维斯分校和德克萨斯大学奥斯汀分校的NEES设备场地。地形效应是指在山坡、山脊和峡谷等地形特征附近的地震地面运动的修改和放大。这一有据可查的现象尚未在设计规范中得到解决。由于构造和地形是密切相关的，世界上大多数地震活跃区都有明显的地形起伏。近几十年来，人口增长和未开发的大都市土地稀缺改变了城市土地使用模式，并将越来越多的人口和基础设施资产置于地震时易受地形影响的地区。虽然人们普遍认为，地形放大可以提高地震风险，目前还没有就如何可靠地量化其影响达成共识。由于缺乏共识，无法就如何在实践中考虑到这一现象制定可接受的准则，从而在日常设计中忽略了造成地震危险的一个重要因素。到目前为止，一个主要的障碍，了解和逼真地模拟地形的影响一直是缺乏一个统计上显着数量的地震记录，从密集的仪器与地形特征的网站。此外，虽然现有的理论模型一般能够定性预测不规则的地形特征对地震地面运动的影响，仍然有显着的定量预测和观测之间的分歧。本研究解决了这个问题的地形放大地面运动的研究，将包括一个全面的综合方案的实验模拟，现场测量，经验数据分析和数值模拟。这些研究方法，在一个框架中一起应用，现在可能由NEES，将迅速和大幅推进地形效应的理解。这一新的理解反过来又将允许开发数据和分析驱动的准则，以说明这些影响在工程设计，建筑规范规定，地震风险和小区划研究。智力优势：这项研究整合了从以下方面获得的关于地形影响的知识：（一）离心模型试验（使用加州大学戴维斯分校的NEES土工离心机）的地形特征，（ii）现场数据获得的临时，当地密集的仪器阵列（使用德克萨斯大学的NEES移动的设备，奥斯汀和宽带传感器来自地震学联合研究所（IRIS）大陆岩石圈阵列地震研究计划（PASSCAL）），记录了频繁和可预测的应力-在犹他州的山区诱发采矿地震活动，（iii）严格的数值模拟研究，和（iv）下一代衰减强地面运动数据库的统计分析。预计这项工作将产生以下成果：（i）关于地形放大的高质量数据数量的数量级增加，（ii）对这一现象的更深入的基本理解，（iii）地形对地面运动的影响的量化，（iv）解释地形放大的改进的衰减关系，及（v）广泛采用的准则及条文，以顾及实际上的地震危险。最终，这项研究的成果将使地震风险得到更有效地管理地面运动量化和现场响应prediction.Broader影响：该项目实施了一个新的桥梁博士学位计划（BDP），面向教育在地震工程领域的代表性不足的学生。BDP也可以作为一个模式，以增加大型合作科学，工程和技术研究项目的多样性。 虽然这项研究的重点是与地震反应有关的问题，但基础知识将与其他灾害有关，如自然地形中的滑坡和大坝、堤坝和堤坝的稳定性。该项目的数据将通过NEES数据库存档并向公众提供。

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 Washington State University (lead institution), Drexel University (subaward), Georgia Institute of Technology (subaward), University of Arkansas (subaward), and University of Puerto Rico, Mayaguez (subaward). This project will utilize the NEES equipment sites at the University of California, Davis and the University at Texas, Austin. Topographic effects refer to the modification and amplification of seismic ground motion in the vicinity of topographic features such as hillsides, ridges, and canyons. This well-documented phenomenon has yet to be addressed in design codes. Because tectonics and topography are closely related, most seismically active regions of the world are marked by significant topographic relief. In recent decades, population growth and scarcity of undeveloped metropolitan land have changed urban land use patterns and placed an increasing number of people and infrastructure assets in areas susceptible to topographic effects during earthquakes. Although it is widely recognized that topographic amplification can elevate seismic risk, there is currently no consensus on how to reliably quantify its effects. Lack of consensus has precluded development of acceptable guidelines on how to account for this phenomenon in practice, thus leaving an important factor contributing to seismic hazard unaccounted for in routine design. Until now, a major impediment towards understanding and realistically modeling topographic effects has been the lack of a statistically significant number of seismic recordings from densely instrumented sites with topographic features. Moreover, while existing theoretical models are generally capable of qualitatively predicting the effects of irregular topographic features on seismic ground motion, there is still significant quantitative disagreement between predictions and observations. This research addresses this problem with a study of topographic amplification of ground motion that will include a comprehensive and integrated program of experimental simulations, field measurements, empirical data analysis, and numerical modeling. These research methods, applied together in a framework now made possible by NEES, will quickly and substantially advance the understanding of topographic effects. This new understanding will in turn permit the development of data- and analysis-driven guidelines to account for these effects in engineering design, building code provisions, and seismic risk and microzonation studies. Intellectual Merit: This research integrates knowledge about topographic effects gained from: (i) centrifuge model testing (using the NEES geotechnical centrifuge at the University of California, Davis) of topographic features, (ii) field data acquired with temporary, locally-dense instrumentation arrays (using the NEES mobile equipment at the University of Texas, Austin and broadband sensors from the Incorporated Research Institutions for Seismology (IRIS) Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL)) recording frequent and predictable stress-induced mining seismicity in a mountainous region of Utah, (iii) rigorous numerical modeling studies, and (iv) statistical analyses of the Next Generation Attenuation strong ground motion data base. It is envisioned that this work will result in: (i) an order-of-magnitude increase in the amount of high quality data on topographic amplification, (ii) greater fundamental understanding of this phenomenon, (iii) quantification of topographic effects on ground motions, (iv) improved attenuation relationships that account for topographic amplification, and (v) widely adopted guidelines and provisions to account for this seismic hazard in practice. Ultimately, the outcomes of this research will allow seismic risk to be more effectively managed in terms of ground motion quantification and site response prediction.Broader Impacts: This project implements a new Bridge to Doctorate Program (BDP) geared towards educating underrepresented students in the field of earthquake engineering. The BDP can also serve as a model for increasing diversity in large collaborative science, engineering and technology research projects. While this research focuses on issues related to seismic response, the fundamental knowledge will have relevance to other hazards, such as landslides in natural terrain and the stability of dams, levees, and embankments. Data from this project will be archived and made available to the public through the NEES data repository.