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Earthquake Motion Characteristics of Reclaimed Ground in Osaka Bay Erea

大阪湾地区填海区地震运动特征

基本信息

批准号：
03650468
负责人：
OHBA Shintaro
金额：
$ 1.47万
依托单位：
Osaka Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The Osaka Plain is surrounded by mountainous regions and is located in the northeast of an oval-shaped basin, comprising part of the Osaka Bay, with a 40 km minor axis and 80 km major axis. The earthquake motions in the Osaka Plain are greatly influenced by the topographical conditions and the ground conditionsThis report studies the duration time, predominant period and amplification characteristics of earthquake motions in the reclaimed ground, based on the data gathered through earthquake observation.The discussion revealed the following :(1) Duration timeThe duration of earthquake motions in the Osaka Plain varies with the horizontal distance between the surrounding mountains and the location in the plain ; the duration time is short in areas on the border between the mountains and plain, while it is markedly longer in the central part of the plain. This variation in the duration of earthquake motions is not caused by the difference in the conditions of the surface layer, such as that between a diluvial layer and an alluvial layer. It results from the fact that the synthesis of S waves from below, corresponding to main motions, and surface waves propagated horizontally through the sedimentary layer, corresponding to delayed motions.(2) Predominant periodThe short periods (less than approx. 1 second) prevail in the portion of the wavefrom corresponding to main motions. The predominant periods shorter than approx. 1 second reflect the structure of the uppermost part of the ground. The periods longer than approx. 1 second mainly prevail at the portion of the wavefrom corresponding to the delayed motions.(3) Amplification characteristicIn the periodic band shorter than approx. 1 second, the amplification characteristics of earthquake motions in the reclaimed ground vary conspicuously according to the structure of subsurface layers, up to approx. 60 m under the surface.

大坂平原被山区包围，位于一个椭圆形盆地的东北部，包括大坂湾的一部分，短轴40公里，长轴80公里。大坂平原的地震动受地形条件和场地条件的影响很大，本文根据地震观测资料，研究了填海造地的地震动持续时间、卓越周期和放大特性，结果表明：（1）持续时间大坂平原地震动持续时间随周围山脉与平原位置的水平距离而变化;山地与平原交界处持续时间较短，平原中部持续时间明显较长。地震运动持续时间的这种变化不是由表层条件的差异引起的，例如洪积层和冲积层之间的差异。这是由于来自下方的S波（对应于主运动）和通过沉积层水平传播的面波（对应于延迟运动）的合成。(2)主导周期短周期（小于约。1秒）在对应于主运动的那部分波形中占优势。主要周期短于约。1秒反映了地面最上部的结构。时间比接近。1秒主要在对应于延迟运动的波型部分占优势。(3)放大特性在周期带短于约。第二，地震运动的放大特性在填海地面的变化显着，根据结构的地下层，高达约。地下60米。