| 講演要旨(和文) | | 堤防や道路盛土上で表面波探査を実施した際に，表面波相の前後に明瞭なP波SV波反射波比定相が捉えられることがある．表面波探査データに含まれるこれらの反射波相に対して通常の反射法探査データ処理を施し，P波およびS波反射断面を作成することができることを示してきた．また構築した反射断面から詳細な浅部地盤構造の評価ができることを示してきた．一方で求めた反射法処理探査断面が表面波探査解析結果などと合致しない場合も見られた．今回，ジオメトリを定義し直し，再処理したところ，VSP解析や土質ボーリング結果等と整合的な断面を得ることができた．本報告では，軟弱地盤上に構築された道路高盛土の崩落現場および熊本地震被災地において実施した表面波探査のデータ解析処理を主対象に，データ取得，処理解析および断面解釈結果を紹介し，表面波探査とそのデータの活用展開の可能性について述べる． |
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| | 講演要旨(英文) | | Distinct P- and SV-wave reflection events are often observed in datasets of high-resolution active surface wave surveys. Accordingly, it is capable of applying usual P- and S-wave seismic reflection processing to the acquired dataset along with the conventional multichannel analysis of surface waves. In particular, the SV-wave reflection section can provide detailed geological structure of the near surface. We conducted a detailed and repeated field measurement at a site where road embankment had partly collapsed. The survey consisted of the hybrid surface wave survey, DC resistivity survey, GPR, and high-frequency surface wave measurement along a total of 10 survey lines. S-wave VSP measurements were also carried out at two points in the site. Furthermore, P- and S-wave seismic reflection processing was applied to a total of 5 datasets of active surface wave survey. As a result, the depth sections were fundamentally concordant with S-wave velocity sections reconstructed from surface wave survey data, and with S-wave VSP results. In conclusion, seismic reflection analysis is effective, when conducting an active surface wave survey densely comparable to the conventional seismic reflection surveying, for the comprehensive interpretation of the near surfaces. |
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