| 講演要旨(和文) | | 筆者らはこれまでに，リニアアレイ微動探査（Linear Array Microtremor Survey: LAMS）を大規模河川堤防の調査に適用し，多チャンネル表面波探査（Multichannel Analysis of Surface Waves：MASW）では測定困難なほど交通振動の大きい条件でも，堤体から基礎地盤までのS波速度断面を得られることを報告した（北ほか、2013）．その後筆者らは，同じ測定機器を用いて，同じ測線でMASWとLAMSをほぼ同時に実施した．その結果，LAMSの分散曲線がより低周波まで延びているが，両分散曲線は良く一致することが確認できた．一方，MASWで得た分散曲線はLAMSより堤体部のS波速度の変化に敏感であった． 筆者らは，このMASWとLAMSを合わせて測定・解析する方法をハイブリット型表面波探査と呼び，高分解能と深い探査深度を両立できることを確認した． |
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| | 講演要旨(英文) | | The authors had reported that LAMS (Linear Array Microtremor Survey Method) is an advanced technique to be used at high-levees to obtain S-wave velocity structures from the levee crown to its substrata particularly when site conditions are affected by high levels of ambient road vibrations which are generally an obstacle to obtaining high quality MASW (Multichannel Analysis of Surface Waves) records (Kita et al, 2013). After the last report, we conducted several LAMS and MASW measurements at almost same time along the same survey lines using a common measurement system. As a result, we verified that dispersion curves obtained from LAMS measurements agreed well with the dispersion curves obtained via MASW measurements except that LAMS's dispersion curves also revealed phase velocities at lower frequency ranges. On the other hand, dispersion curves obtained via MASW measurements were more sensitive to changes of S-wave velocities in shallow layers than the dispersion curves obtained via LAMS. The authors have called this new survey approach which combines MASW and LAMS, the Hybrid Surface Wave Method. We verified that the Hybrid Surface Wave Method offers higher S wave structure resolutions and deeper investigation depths. |
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