Analysis of locally concentrated strong motions of multi-phased and irregularly layered grounds of the time-dependent frequency response characteristics

多相不规则层状地基局部集中强运动的时变频率响应特性分析

• 批准号: 11650490
• 负责人: AKIYOSHI Takashi
• 金额: $ 0.51万
• 依托单位: Kumamoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650490/
• 关键词: site effects; irregularly layered ground; liquefaction; non-stationary transfer function; natural frequency; shear modulus; absorbing boundary; 2-phase medium

For the basic and best understading of "the seismic disaster belt " for the 1995 Hyogoken-Nanbu-earthquake, this study aims to analyze the mutual effects of dynamic characteristics of both rock-based mountain sites and liquefaction-based coastal sites, and also the inducing process of the belt based on the mutual relations between irregular layering and seismic intensity. Numerical computation is performed for the 2D basic ground models and site ground models at Kobe for the 1995 Hyogoken-Nanbu earthquake which was recorded at Port Island of Kobe below 32m of ground surface, using the non-linear dynamic analysis program with the absorbing boundaries which is developed based on the effective stress analysis method.The following is the summary :1. In advance of the analysis, an absorbing boundary condition for eliminating reflection waves from artificial boundaries is developed, introduced into the existing program for effective stress analysis, and finally shows the effectiveness.2. In … More irregularly layered grounds, liquefaction rapidly lowers the soil stiffness and stimulates the shrinkage and non-linearity of the acceleration-frequency response function at sites due to the extension of the natural frequency. This means that the frequency response functions at sites transfer to low-pass filters.3. The dynamic characteristics around boundary faces between horizontally adjacent layers are subjected to harder ground for the case of extremely different stiffnesses and to both grounds for the case of mutually similar stiffnesses.4. Increment of seismic intensity lowers the acceleration response due to liquefaction along the coastal area of surface layers and therefore induces high concentrated area of acceleration response at the surface ground of irregularly layered mountain sites. Though this seismic disaster belt appeared based on the specific combination of Kobe ground and Kobe earthquake of the maximum acceleration 5.4m/s^2, the belt will appear also at other cities because Kobe grounds exist at almost coastal cities in Japan. Less

为了更好地理解1995年日本南部地震的“地震灾害带”，本文从不规则分层与地震烈度的相互关系出发，分析了岩性山地场地和液化海岸场地的动力特性的相互作用，以及地震灾害带的诱发过程。利用基于有效应力分析方法开发的具有吸收边界的非线性动力分析程序，对1995年神户港岛32米以下的神户神户地震的二维基本地面模型和场地地面模型进行了数值计算。总结如下：1.在分析之前，建立了消除人工边界反射波的吸收边界条件，并将其引入到现有的有效应力分析程序中，最后说明了其有效性。在…中在较多的不规则层状地基中，由于自振频率的扩展，液化迅速降低了土体的刚度，并刺激了场地处加速度-频率响应函数的收缩和非线性。这意味着站点的频率响应函数转移到低通滤波器。水平相邻层间边界面处的动力特性在刚度极大不同的情况下会受到较硬的影响，而在刚度相近的情况下则会受到两种情况的影响。地震烈度的增加降低了地表近岸液化引起的加速度响应，从而在不规则层状山地场地的地表引起了加速度响应的高度集中区域。虽然这条地震灾害带是基于神户地面和神户地震的特定组合而出现的，最大加速度为5.4米/S^2，但由于日本沿海城市几乎都存在神户地面，因此其他城市也会出现这一地震灾害带。较少

项目成果

AKIYOSHI,T., FUCHIDA,K., SHIRINASHIHA,S.and TAJIMA,S.: "Effects of irregularity and liquefaction of grounds on the local amplification characteristics of earthquakes(in Japanese)"Proc.25^<th> JSCE Earthq.Engng.Symp.. 189-192 (1999)

AKIYOSHI,T.、FUCHIDA,K.、SHIRINASHIHA,S. 和 TAJIMA,S.：“地面不规则性和液化对地震局部放大特性的影响（日语）”Proc.25^<th> JSCE Earthq。

秋吉卓: "Site effects on nonlinear seismic response of Layered grounds"Proc.2nd Int.Conf.on Earthquake Resistant Ergineering Structures. 737-746 (1999)

Taku Akiyoshi：“分层地面非线性地震响应的场地效应”Proc.2nd Int.Conf.on Earthquake Resistant Engineering Structures 737-746 (1999)。

秋吉卓: "Site effects on seismic response of nonlinear layered grounds"CD-ROM Proc.12th World Conf.on Earthq.Engng.. (Paper No.171). (2000)

Taku Akiyoshi：“场地对非线性层状地面地震响应的影响”CD-ROM Proc.12th World Conf.on Earthq.Engng..（论文第171号）。

AKIYOSHI,T., SHIRINASHIHAMA,S., FUCHIDA,K.and SUN, X.: "Site effects on nonlinear seismic response of layered grounds"Proc.2^<nd> Int.Conf.on Earthq.Resist.Engng.Struct. 737-746 (1999)

AKIYOSHI,T.、SHIRINASHIHAMA,S.、FUCHIDA,K. 和 SUN, X.：“层状地面非线性地震响应的场地效应”Proc.2^<nd> Int.Conf.on Earthq.Resist.Engng.Struct

秋吉卓: "Site effects on nonlinear seismic response of layered grounds"Proc.2nd Int.Conf.on Earthquake Resistant Engineesing Structures. 737-746 (1999)

Taku Akiyoshi：“层状地面非线性地震响应的场地效应”Proc.2nd Int.Conf.on Earthquake Resistant Engineering Structures 737-746 (1999)。