| 講演要旨(和文) | | 新潟県関屋分水路の河口部において護岸コンクリート背面の空洞調査を目的とした物理探査を実施した.当地周辺では,県管理の海岸護岸で陥没事故が発生しており,河川護岸においても陥没の原因となる空洞の発生が懸念された.適用した探査手法はGPR,打音ウェーブレット解析,高周波加速度アレイ計測の3種である.探査対象としたのは,高水護岸及び小段部にある無筋のコンクリート床板で,一部に亀裂が認められていた.探査の結果,ジョイント部や亀裂発生部,ならびに照明塔近傍で空洞に比定される信号異常が認められた. |
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| | 講演要旨(英文) | | A combined geophysical survey was conducted to detect cavities behind a concrete revetment founded at the mouth of Sekiya Shortcut, Niigata Prefecture. A collapse that had taken place behind a concrete seawall close to the test site alarmed potential development of cavity in backfills behind the river revetment. The tested geophysical methods involved ground penetrating radar survey, wavelet analysis of hammer impact-induced sound, and multichannel accelerometer array measurement of hammer impact-induced waves. Twenty-cm thick plain concrete slabs at the lower flat and berm were the target. Clear cracks partly developed in the slabs, and some joints entirely opened. As a result, significant anomalies were identified just close to the open joints, clear cracks and a lighting pole. |
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