An advanced Research on the Structural Dynamics due to Short-Period Surface Waves with Emphasis on Applications to Practice

用拟规范法编制了水平不规则地基地震反应分析软件。特别强调了土壤的非线性特性的介绍以及程序的复杂性。为了将我们的软件应用于实践，我们选择了仙台市的不规则场地作为测试场地。仙台市因1978年宫城县冲绳大地震而遭受严重破坏。自地震以来，仙台市已经扩展到土壤较软的地区，增加了人们对不久的将来发生更具破坏性的大地震的担忧。为了研究仙台的强地面运动，我们于1997年在那里安装了一套地面运动阵列观测系统。该阵列系统名为Snall-Titan，由20个观测站和一个控制中心组成。在仙台地区强震活动的刺激下，截至2004年2月，该系统共获得了250次地震的许多运动记录。我们首先从场地局部效应的角度讨论了仙台盆地的地面运动观测结果，结果表明，不同场地的地面运动的放大程度不同，并且在盆地的软沉积地区表现出显著的差异。并分析了软矿区不同区位的放大差异。由此分析得出盆地构造的边缘效应对软弱堆积区地面运动的重要性。为了弄清边缘效应的机制，我们用二维伪谱方法模拟了仙台盆地。在盆地构造模型的基础上，对地面运动进行了二维分析，并将分析结果与观测结果进行了比较。对比表明，边缘效应对盆地构造软岩地区的运动具有重要的放大作用。

We have developed, some softwares for the earthquake response analysis of horizontally irregular grounds using the Pseudo-spectural method. Especially emphasis was placed on the introduction of nonlinear characteristics of soils as well as on the sophistications of programs. For the purpose of applications of our softwares to practice, we selected the irregular ground in Sendai City as a test site. Sendai City suffered severe damage due to the 1978 Miyagiken-Oki Earthquake. Since the earthquake, Sendai City has extended into areas composed of softer soils, increasing the anxieties of more devastating disaster by a great earthquake in the near future. In order to investigate strong-ground motions in Sendai, we installed there an array observation system of ground motions in 1997. The array system, named Snall-Titan, consists of 20 observation stations and one control center. Stimulated by the high seismicity in the Sendai district, the system has obtained many motion records resulting from a total of 250 earthquakes as of February in 2004. We first discussed observation results of ground motions in the Sendai basin from the point of view of local site effects, showing that amplifications of ground motions vary from site to site and arc remarkable in the soft deposit areas of the basin. The differences in amplifications between locations of the soft deposit areas were also analyzed. This analysis led to the importance of the edge effects of basin structure on the ground motions of the soft deposit areas. In order to make clear the mechanism of the edge effects, we modeled the Sendai basin using a two-dimensional Pseudo-Spectral Method. Based on-the model of basin structure, we made two-dimensional analyses of ground motions and compare the analyzed results with the observed. Comparisons show that the edge effects play an important role in amplifying motions in the soft deposit area of basin structure.