広域の強震記録から推定される2011 年東北地方太平洋沖地震の表層地盤の非線形挙動  [in Japanese] Nonlinear Behavior of Soft Soil Deposits during the 2011 Off the Pacific Coast of Tohoku Earthquake Based on Strong Motion Records in Wide Area of East Japan  [in Japanese]

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Author(s)

    • 若井 淳 WAKAI Atsushi
    • 港湾空港技術研究所地震動研究チーム Port and Airport Research Institute, Engineering Seismology Division
    • 野津 厚 NOZU Atsushi
    • 港湾空港技術研究所地震動研究チーム Port and Airport Research Institute, Engineering Seismology Division

Abstract

地震動が構造物に与える影響を正確に理解する上で、表層地盤の非線形挙動が地震動に与える影響を評価することは重要である。2011年東北地方太平洋沖地震では、全国をカバーする強震観測網により、非常に広範な地域で強震記録が得られている。本研究では、これらの記録を用い、地震動強さを表すいくつかの指標と非線形挙動強さとの関係を調べ、それらの関係を適切に表現する経験式を提案した。その結果、非線形挙動強さはPGVと最も相関が良く、その関係は双曲線モデルで最も適切に表現されることがわかった。また、非線形挙動強さの経験式からの偏差が線形時のサイト増幅特性のピーク周波数と相関があることがわかった。

In order to understand the effects of strong ground motions on engineering structures, it is important to evaluate the effects of soil nonlinearity on strong ground motions. In this paper, based on strong motion records obtained in wide area during the 2011 Off the Pacific Coast of Tohoku earthquake, degree of soil nonlinearity was evaluated based on the shift of peak frequencies from linear site amplification factors to observed Fourier spectra during the Tohoku earthquake. Then, the relation between the degree of soil nonlinearity and ground motion indices such as PGA, PGV and PSI was investigated. It was found that the degree of soil nonlinearity was best correlated with PGV and the relation can be approximated with a hyperbolic curve. In addition, it was found that the deviation from this empirical formula is correlated with the peak frequencies of linear site amplification factors.

Journal

  • Journal of Japan Association for Earthquake Engineering

    Journal of Japan Association for Earthquake Engineering (12), 4_160-4_176, 2012

    JAPAN ASSOCIATION FOR EARTHQUAKE ENGINEERING

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