Response of Earth Dams to Spatially-Varying Earthquake- Induced Ground Motion

该研究项目的目的是研究空间变化的地震地面运动引起的坝基差异激励的影响。标准程序是假设大坝底部的所有点同时经历相同的地震引起的地面运动--也就是，大坝因其所在的刚性板的运动而摇晃。相反，这项研究考虑了由地震波的传播和散射引起的基本激励的相位延迟和非相干效应。现在，通过分析和随机模拟地坝和近地坝上最近的加速度记录仪记录，可以获得适当的地面运动数据。研究程序包括：1)从这些数据中选择合适的地震动模型；2)对三维土坝模型进行线性随机振动分析，研究空间变化地震动的影响；3)开发近似的激励规范，当使用两个激励规范分析大坝时产生合理的响应。维度模型；4)地形影响的初步评价；5)用等效线性化方法研究非线性响应，并通过蒙特卡罗模拟进行了验证。研究结果对既有土坝的安全评价以及新土坝的设计具有一定的参考价值。

The objective of this research project is to study the effects of differential excitations along the base of a dam, caused by spatially varying earthquake ground motion. The standard procedure is to assume that all points at the base of the dam simultaneously experience the same earthquake-induced ground motion - that is, that the dam is shaken by the motion of a rigid plate on which it rests. In contrast, this study accounts for phase delay and incoherence effects of the base excitations arising from the propagation and scattering of seismic waves. Appropriate ground motion data are now available from the analysis and stochastic modeling of recent accelerograph recordings on and near earth dams. The research program involves: 1) The selection of a suitable ground motion model from these data; 2) A linear random vibration analysis of a three-dimensional earth dam model to study the effects of spatially varying ground motions; 3) The development of approximate excitation specifications that yield reasonable responses when the dam is analyzed using a two- dimensional model; 4) A preliminary assessment of topographical effects; 5) Investigation of the non-linear response using the method of equivalent linearization, with verification by Monte Carlo simulation. The results from this research are relevant to safety evaluations of existing earth dams, as well as to the design of new earth dams.