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High frequency response of a sediment-filled valley for seismic waves

充满沉积物的山谷对地震波的高频响应

基本信息

批准号：
02650399
负责人：
SHINOZAKI Yuzo
金额：
$ 1.34万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02650399/
关键词：
Subsurface irregular ground High frequency response Earthquake damages Wave propagation characteristics Boundary integral equation Discrete wave number method Full-scale forced vibration test Servohydraulic-type vibrator 短周期地振動

项目摘要

Time-domain responses as well as frequency-domain responses of a sediment-filled valley for incident SH waves are studied with the emphasis of site responses for high frequencies(>1 Hz)which are of interest in earthquake engineering. We calculate them using a boundary integral equation method in which Green's functions are evaluated using the discrete wave number method. Calculating frequency-domain responses as well as time-domain responses of the sediment-filled valley, we discuss in details effects of inclined interfaces of the valley upon wave amplification patterns, propagation of Love waves and duration of the ground shaking in the valley.Some spectral ratios of surface ground motion to bedrock motion are also calculated based on the acceleration responses at several sites due to an artificial earthquake ground input motion which has relatively high predominant frequencies and they are compared with spectral ratios of the flat layer response to bedrock motion. It is shown that since Love waves generated by the inclined interface have a great influence on the responses of the valley, spectral ratios of sediment-filled valley become more broad-band than that of the flat layer response.Propagation characteristics of harmonic waves by subsurface irregularities is studied experimentally with the detailed measurements of a surface ground motion generated by forced vibration of a reinforced concrete model footing placed on a subsurface irregular ground. Each of three different footings was excited in three kinds of directions to generate different patterns of wave propagation. We evaluated particle orbits, coherence function and phase information from the cross-power spectrum between adjacent sites and constructed phase velocitv dispersion curves to investigate wave propagation characteristics on subsurface irregular ground. It is shown that dispersion data measured on less irregular subsurface ground are in good agreement with the theoretical values.

本文研究了SH波入射时填砂河谷的时域和频域反应，重点研究了地震工程中感兴趣的高频（> 1Hz）场地反应。我们使用边界积分方程方法计算它们，其中使用离散波数方法计算绿色函数。通过计算填沙河谷的频域响应和时域响应，详细讨论了河谷倾斜界面对波浪放大模式的影响，本文还根据几个场地的人工地震加速度反应计算了地表地震动与基岩地震动的谱比运动具有相对较高的主导频率，并将它们与基岩运动的平坦层响应的谱比进行比较。结果表明，由于倾斜界面产生的Love波对山谷的响应有很大的影响，沉积物充填山谷的光谱比变得更宽，本文通过对一个钢筋混凝土基础模型的受迫振动引起的地面运动的详细测量，对地下不规则结构引起的谐波传播特性进行了实验研究。地下不规则地面。三个不同的基础中的每一个都在三种方向上被激发，以产生不同的波传播模式。通过计算相邻场地间互功率谱中的粒子轨道、相干函数和相位信息，构造了相速度频散曲线，研究了地下不规则地面上的波传播特性。结果表明，在不太不规则的地下地面上测量的频散数据与理论值吻合得很好。