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| | Abstract | | 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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