Performance of Earth Dams During the Whittier Narrows Earthquake of October 1, 1987

一些土石坝安装了强震记录仪，经历了1987年10月1日的惠蒂尔纳罗斯地震。距离最近的是距离震中4公里的惠蒂尔水坝。坝顶的最大水平加速度为0.32g，上游记录的最大垂直加速度为0.46g。也得到了距离较大的其他大坝的响应。对于这样的结构，几乎没有强震记录。该项目对9个土坝的这些记录进行了分析，以了解土坝的行为，并利用不同的分析模型来分析大坝的反应。主震期间的震动以及余震触发了九座大坝上的所有加速度计，提供了美国和国外迄今获得的最广泛的土坝地震反应测量结果。这是加州理工学院和南加州大学的合作项目。主要工作有三个：(1)数据处理、分析和加速度曲线的比较；(2)大坝内部永久变形和裂缝的评估；(3)总结观测、结果和结论，提出土坝抗震加固的总体建议。加州理工学院正专注于对其中一到两座大坝的物理模型进行离心机测试，而南加州大学则专注于九座大坝的简化和复杂数值模型。比较了离心机试验结果、惠蒂尔窄地震时大坝的观测反应和用数值模型进行计算机分析的结果。

A number of earth and rockfill dams, instrumented with strong ground motion recorders, experienced the Whittier Narrows earthquake of October 1, 1987. The closest was the Whittier Narrows Dam, at 4 kilometers distance from the earthquake's epicenter. The maximum horizontal acceleration was 0.32g recorded at the crest of the dam, while the upstream recorder indicated a peak vertical acceleration of 0.46g. The response of other dams at greater distances was also obtained. Few strong motion records are available for such structures. This project addresses the analysis of these records from nine earth dams in order to understand the behavior of earth dams, and the utility of different analytical models for the analysis of dam response. The shaking during the main shock, as well as the after shocks, triggered all accelerographs on the nine dams, providing the most extensive array of earthquake response measurements of earth dams yet obtained in the U.S. and abroad. It is a cooperative project between the California Institute of Technology and the University of Southern California. Three major tasks are being addressed: (1) data processing, analysis, and comparison of accelerograms; (2) evaluation of internal permanent deformation and cracking in the dams; and (3) summarizing the observations, results, and conclusions in a general recommendation for the strengthening of earth dams for earthquake resistance. The California Institute of Technology is concentrating on performing centrifuge tests on physical models of one or two of these dams, while the University of Southern California is concentrating on both simplified and complex numerical models of nine dams. A comparison is being made of the results of the centrifuge tests, the observed response of the dams during the Whittier Narrows earthquakes, and the results of the computer analysis using the numerical models.