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The effects of surface geometry tree and buildings on distribution of wave propagation

表面几何树和建筑物对波传播分布的影响

基本信息

批准号：
14350237
负责人：
IWASHTTA Kazuyoshi
金额：
$ 6.72万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350237/
关键词：
Earthquake Strong motion surface geometry Vibration Tree Building Wave Propagation 強震動地盤震動木振動

项目摘要

It is well known that the most fundamental and important problem in the seismic engineering is estimation of the surface ground motion caused by earthquake. Usually, to evaluate the surface ground motion and wave propagation in the surface layer, the ground is modeled as the very simple flay layer system, while the real surface ground is quite irregularly shaped. And the programs, like as SHAKE, based on the wave propagation in simple layer system are applied. In those cases, the ground is assumed as flat and there is nothing on the surface. There are many local and micro geographical features on the ground surface. On the ground, there may be many trees, forests, houses and buildings. There is a possibility that wave propagation is affected these features, In this study, the effects of these omitted phenomena on the wave propagations are evaluated.Seismic responses of a ground with various types of sinusoidal shaped irregularity were evaluated by using the boundary element method and … More analyzed based on "scattered-wave contribution". The examination of the numerical results revealed the following : 1)the response at the trough varies sharply with frequency whereas the response at the peak shows large amplification over a wide frequency range ; 2)the predominant frequencies at the trough depend on the amplitude of the surface irregularity and do not depend on the number of fluctuations of the ground ; and 3)these characteristics can be understood as the results of the interference of scattered waves coming from the irregular surface.Peak ground acceleration(PGA) as a measure of earthquake motion intensity is an important factor in the earthquake-resistant design and reliability analysis of structures. The purpose of this article is to examine the spatial variability of PGAS (recorded at the same epicentral distance) as a function of separation distance. To do this, we define PGA ratios as spatial intraevent variations of PGAS and examine their statistical characteristics. We analyze the probability distribution of the ratios and formulate equations for their probability density functions, mean values, standard deviations, and percentiles. These statistics are then estimated using accelerometer arrays of the Chiba, SMART-1, and SIGNAL databases. Then, the relationship between these statistics and the station separation distances is analyzed. We found that the means and standard deviations have an almost linear relationship with the logarithm of the station separation distances ranging from several meters to 100 km. Finally, based on the fiftieth and ninety-fifth percentiles, the differences between PGAS at two different sites due to future earthquakes are discussed. Less

众所周知，地震工程中最基本和最重要的问题是地震引起的地面运动估计。通常，为了计算地表地震动和波在表层中的传播，地面被模拟为非常简单的表层系统，而真实的地表是非常不规则的。并应用了SHAKE等基于简单层状体系的波传播程序。在这些情况下，地面被假定为平坦的，表面上没有任何东西。地表具有许多局部和微地理特征。在地面上，可能有许多树木，森林，房屋和建筑物。本文利用边界元法计算了不同形状的正弦形不规则场地的地震反应，并与实验结果进行了比较。 ...更多信息基于“散射波贡献”进行分析。对数值结果的检验表明：（1）波谷处的响应随频率变化剧烈，而波峰处的响应在很宽的频率范围内表现出很大的放大作用：（2）波谷处的优势频率取决于地面起伏的幅度，而不取决于地面起伏的次数;地震动峰值加速度（PGA）作为地震动烈度的一种度量，是结构抗震设计和可靠性分析的重要指标。本文的目的是研究的空间变异性PGAS（记录在同一震中距离）作为一个函数的分离距离。要做到这一点，我们定义PGA比率的空间事件内变化的PGAS和检查他们的统计特征。我们分析了比率的概率分布，并制定了其概率密度函数、平均值、标准差和百分位数的方程。然后，使用千叶、SMART-1和SIGNAL数据库的加速度计阵列估计这些统计数据。然后，这些统计量和站间距之间的关系进行了分析。我们发现，平均值和标准差有一个几乎线性的关系，从几米到100公里的站间距的对数。最后，根据第50次和第95次地震，讨论了两个不同地点的PGAS由于未来地震的差异。少