A Study on Amplification Characteristics of Seismic Ground Motions on Irregularly Layered Structures

L。详细研究地形和地下条件对地震动行为的影响是地震工程学的一项重要任务。为了验证地形地质条件对地震动性态的影响，以丰桥工业大学为研究区域，建立了台阵地震动场系统，迄今共记录到8次地震。对这些数据进行了时间域和频域分析。在此基础上，根据调查区域的实际地面条件进行了响应分析。实验与理论分析的对比结果如下：1.实验结果与理论分析对比。研究结果表明：(1)振幅最大的共振频率不依赖于软土局部深度；(2)振幅在谷底中心处最大，在谷底两端逐渐减小；(3)谷底的放大特性不受入射波角和地面阻抗的影响。(4)目前，为了计算复杂层状结构的三维响应，采用了延拓Aki-Larner技术。1992学年，在此基础上安装了加速度计，并设计了调查区域的三维模型。因此，该系统作为强震观测的射线系统完成，用于研究不规则层状结构上地震动放大特性。在未来，我们将进行地震动观测以及实验和理论分析。

l. Details of researchTo elucidate the effects of topography and underground conditions in behavior of ground motions is an important task in earthquake engineering. In order to prove the effects of topographical and geological conditions in behavior- of ground motions, an array system foiseismic ground motion was set up around Toyohashi University of Technology as the investigated area, and until now eight times of earthquake have been recorded in total. These data were analyzed in time and frequency domain. Further more, response analysis based on actual ground conditions of the investigated area has been performed. The results of comparison between experimental and theoretical analysis are as follows.2. Results of research(1) The resonance frequency with maximum amplitude does not depend on the local depth of the soft soil.(2) Amplitudes are the largest at the center of the valley, and are getting smaller as nearing on the both ends of the valley.(3) Amplification characteristics of the valley are not influenced by the incident angle of the wave and the impedance of the ground.(4) At present, to calculate the three-dimensional response of complicated layered structures, the extending Aki-Larner technique is carried out.3. Research program for the futureIn 1992 academic year, an accelerometer was installed on the basis and three-dimensional model of the investigated area is designed. So the system is completed as the ai-ray system for strong ground motion observation to investigate the amplification characteristic of seismic ground motions- on irregularly layered structures.In the future, we will practice the ground motion observation and experimental and theoretical analyses.