| 講演要旨(和文) | | 土木研究所と物理探査学会などは、平成25年より実施している「堤防及び河川構造物の総合的な点検・診断技術の実用化に関する研究開発」の一環として、平成26年度に基盤漏水箇所周辺において、高分解能統合物理探査を実施した。具体的には、漏水箇所周辺の堤内地法尻周辺で、比抵抗トモグラフィー（2次元電気探査）と表面波探査を0.5mの測点間隔で行なった、探査結果は、漏水箇所周辺の浅所に高比抵抗、低速度の領域が存在することを画像化できた。これにより、高透水性の礫質土層に浸透した水が、河川水位上昇時に上位シール層の薄い部分から地表に湧出したと推察できた。この結果は、後に土木研究所が行なったコーン貫入試験と整合性が高いことが確認された。これまでの研究により、高分解能統合物理探査は、堤防異常箇所を詳細に調査する手法として有効性が高いことを示すことができた。 |
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| | 講演要旨(英文) | | The authors carried out a High Resolution Integrated Geophysical Investigation into a river levee which had experience of water leakage through its foundation. This study was part of a series of studies conducted since 2013, which have been aimed at the research and development of enhanced investigative and assessment methods for establishing the status of river levees and their relating structures. We performed the electrical resistivity tomography and surface-wave survey at 0.5m spacing along survey lines which were configured around the water leakage at the toe of the landside slope. The survey result revealed a high resistivity and low Vs zone in the vicinity of the leakage. Based on this result, it is likely that increased water level of the river due to rains had raised the water pressure on the sandy gravel layer distributed over shallower part of the foundation resulting in a leakage on the levee landside. This scenario was supported by CPT filed measurements which were carried out by PWRI. We believe therefore that the High Resolution Integrated Geophysical Investigation method has the potential to be a powerful nondestructive method for the detailed inspection of river levees. |
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