| 講演要旨(和文) | | 新潟県中越沖地震で損傷が生じた農業用排水路のシールドトンネルについて,損傷箇所周辺の地山状況を評価するため,トンネル内において2次元表面波探査を実施した.その結果,主損傷区間より20m下流にS波の相対的な低速度帯が認められた.この損傷は,既往調査により地震時の地表地形の影響が要因として挙げられているが,S波速度分布に示される,ボーリング調査では把握されなかった不均質な地質分布の影響を受けた可能性が高い. |
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| | 講演要旨(英文) | | Deformations were caused in the lining of the shield tunnel for agricultural drainage during the Niigataken Chuetsu-oki Earthquake in 2007. To evaluate the ground situation around the deformation part, we executed the surface wave survey in the tunnel. As a result, a low-velocity zone of the S wave was admitted from the main deformation part in 20m downstream. The effect of the surface topography above the tunnel was pointed out by the previous investigation as a factor of these deformations. Additionally, it is thought that these deformations were influenced by ground intensity distribution not understood in the boring exploration shown in the S wave velocity distribution. |
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