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Construction of Index of Quality Factor in Surface Ground for Analysis of Earthquake Ground Motions

地震地震动分析中地表品质因数指标的构建

基本信息

批准号：
17560437
负责人：
TSUJIHARA Osamu
金额：
$ 1.75万
依托单位：
Wakayama National College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17560437/
关键词：
surface ground identification damping earthquake ground motions

项目摘要

National Research Institute for Earth Science and Disaster Prevention (NIED) deploys digital strong-motion seismographs (KiK-net) all over the country in Japan, which provide vertical array records of ground motions. The total number of observation sites is nearly 700. Data observed by KiK-net can be used to identify the dynamic properties of the subsurface ground.In order to identify the properties using KiK-net data, however, some pre-processes such as the correction of sensor direction, wave synthesis, drawing wave, preparation of soil data are needed. Furthermore, the selection of the interval of time series, damping model and initial values used in the analysis of identification must be investigated, because they influence on the results of identification.A new system is developed to identify the quality factor, in which quality factor is swept out of the feasible range in such the frequency band that the quality factor is not sensitive. The system is free from most of the troublesome operations, which makes the various analyses on various conditions possible.Using the system, the dynamic soil properties are identified. The major results in this study are as follows.(1) The trend of quality factor whose values increase according to frequencies can be recognized though the variations are not small enough.(2) The similarity of the estimated values of quality factor can be seen at the identical site using different events of earthquakes.Since the variations of estimated values of quality factor are not small enough, it is too early to discuss its dependency on frequencies quantitatively. Accumulation of analytical results of identification is necessary as well as the development of the method proposed in this study for the goal to model the frequency-dependent quality factor of subsurface ground.

日本国家地球科学与防灾研究所 (NIED) 在日本全国部署数字强震地震仪 (KiK-net)，提供地面运动的垂直阵列记录。观测点总数近700个。KiK-net观测的数据可用于识别地下地面的动力特性。然而，为了利用KiK-net数据识别特性，需要进行一些预处理，如传感器方向校正、波合成、绘制波、土壤数据准备等。此外，辨识分析中使用的时间序列区间、阻尼模型和初始值的选择也必须进行研究，因为它们会影响辨识的结果。开发了一种新的品质因数辨识系统，在品质因数不敏感的频带内将品质因数扫出可行范围。该系统免去了大部分麻烦的操作，这使得对各种条件的各种分析成为可能。使用该系统，可以识别动态土壤特性。本研究的主要结果如下：(1)尽管变化不够小，但可以识别品质因数随频率增加的趋势。(2)在同一地点使用不同地震事件可以看出品质因数估计值的相似性。由于品质因数估计值的变化不够小，定量讨论其对频率的依赖性还为时过早。为了模拟地下地面的频率相关品质因数，识别分析结果的积累以及本研究中提出的方法的发展是必要的。