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

1987年10月1日，许多土坝和石坝都经历了惠蒂尔海峡地震。离震中最近的是距离震中4公里的惠蒂尔窄坝。坝顶记录的最大水平加速度为0.32g，上游记录的最高垂直加速度为0.46g。其他大坝在更远的距离上的反应也得到了。这种结构的强震记录很少。本项目分析了9个土坝的这些记录，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。主震期间和后震期间的震动触发了九座大坝上的所有加速度仪，提供了迄今为止在美国和国外获得的最广泛的土坝地震反应测量数据。这是加州理工学院和南加州大学的合作项目。主要有三个任务：(1)加速度图的数据处理、分析和比较；(2)坝体内部永久变形与开裂评价；(3)总结了土坝抗震加固总建议的观测、结果和结论。加州理工学院正集中精力对其中一两个大坝的物理模型进行离心机测试，而南加州大学则集中精力对9个大坝进行简化和复杂的数值模型研究。将离心机试验的结果、观测到的大坝在惠蒂尔海峡地震中的反应与使用数值模型的计算机分析结果进行了比较。

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.