Site Response and Soil Liquefaction in San Francisco Due to the Loma Prieta Earthquake

洛马普列塔地震造成旧金山的现场响应和土壤液化

• 批准号: 9011458
• 负责人: Thomas O'Rourke
• 金额: $ 7万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-05-15 至 1991-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9011458&HistoricalAwards=false
• 关键词: Site; Response; Soil; Liquefaction; San

This project is part of the NSF/USGS initiative within the National Earthquake Hazard Reduction Program (NEHRP) to investigate the effects of the Loma Prieta earthquake of 17 October 1989. San Francisco offers a unique opportunity to compare the effects of two earthquakes through detailed and comprehensive observations which now exist for the 1906 and the 1989 earthquakes. By studying different locations within the city, it is possible to evaluate how variations in fill thickness and density, the thickness and consolidation state of underlying soft clay, the water table, and the depth to bedrock affect the ground surface response and the development of soil liquefaction for similar levels of bedrock seismic motion. Moreover, ground response coupled with the performance of buried lifeline systems provides an additional chance to quantify the effect of soil-structure interaction on complex networks that are critical for emergency operations. To take advantage of the knowledge gained from the 1906 and 1989 earthquakes, this project is structured according to a three- fold set of objectives: (1) to characterize subsurface ground conditions and site response at select locations in San Francisco - this requires a comprehensive data base on soil conditions, as well as the familiarity and the site-specific knowledge gained from previous investigations and post-earthquake reconnaissance in the city, (2) to model analytically the site response at select locations, and to compare these analytical results with field observations and with seismic data in order to substantiate and refine the analytical models, and (3) to use analytical models to predict the effects on the city of San Francisco of possible future earthquakes that are larger and closer than was the Loma Prieta earthquake. This project involves cooperation with the U.S. Geological Survey (USGS) and San Francisco geotechnical firms and city agencies. The USGS is performing soil boring at selected locations; geotechnical firms are providing soil boring logs (data) and geotechnical investigation reports in order to expand the available data base on subsurface conditions and relevant soil properties. In addition, city agencies, such as the San Francisco Fire Department, are involved in evaluating how the site response characteristics might affect the water supply, and how best to design and operate the pipeline system so as to minimize the effects of locally severe ground shaking and liquefaction.

该项目是美国国家科学基金会/美国地质勘探局在国家减少地震危害方案（NEHRP）下的倡议的一部分，目的是调查1989年10月17日洛马普列塔地震的影响。旧金山提供了一个独特的机会，通过对1906年和1989年地震的详细和全面的观测来比较两次地震的影响。通过研究城市内的不同地点，可以评估填充物厚度和密度的变化、下伏软黏土的厚度和固结状态、地下水位、在相似基岩地震运动水平下，基岩深度影响地表反应和土壤液化的发展。此外,地面响应与埋地生命线系统的性能相结合，为量化对应急行动至关重要的复杂网络中土壤-结构相互作用的影响提供了额外的机会。​为了利用从1906年和1989年地震中获得的知识，本项目的结构是根据三方面的目标：(1)表征旧金山选定地点的地下地面条件和现场反应——这需要一个全面的土壤条件数据库；以及从以前的调查和震后城市勘测中获得的熟悉度和现场特定知识，(2)对选定地点的现场反应进行分析建模；为了将这些分析结果与实地观测和地震数据进行比较，以证实和完善分析模型，(3)利用分析模型预测未来可能发生的比洛马·普里塔地震更大、距离更近的地震对旧金山市的影响。该项目涉及与美国地质调查局（USGS）、旧金山岩土工程公司和城市机构的合作。美国地质勘探局正在选定的地点进行土壤钻孔；岩土工程公司正在提供钻孔测井（数据）和岩土工程调查报告，以便扩大有关地下条件和相关土壤性质的现有数据库。此外，市政机构，如旧金山消防局，也参与评估现场反应特征如何影响供水，如何最好地设计和操作管道系统，以尽量减少当地严重的地面震动和液化的影响。