| 講演要旨(和文) | | 大規模構造物となるフィルダムに対しては，強い地震動に対する堤体の変形による遮水機能の健全性を評価する必要があり，長期間にわたり湛水の浸透状況をモニタリングできる手法を確立することが重要である。著者らはフィルダムにおいて初期湛水開始前および湛水終了後にそれぞれ1回の電気探査測定を行い，堤体材料による室内試験を行った。その結果，湛水開始前に対し湛水終了後に比抵抗が-75%まで低下した領域が上流側のロック材域に集中しており，コア材域および下流側ロック材域では比抵抗の変化は5%〜-20%の範囲を示した。また，室内試験より堤体材料の比抵抗は飽和度の変化が最も支配的となり，飽和度が20%から100%に増加すると比抵抗は-80%まで低下した。よって，電気探査法はフィルダム内部への湛水の浸透状況をモニタリングするのに有効であり，巨大地震に対する堤体全体の遮水性の健全性評価に適用できる可能性が示された。 |
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| | 講演要旨(英文) | | Dams as large-scale structures should be evaluated for the safety of their water sealing performance after transformation of the structure by strong earthquake vibrations. It is very important to establish monitoring techniques to visualize the penetration during filling of the dam for the long term. The authors conducted an electrical exploration during the first filling of a rock-fill dam site, as well as laboratory tests using samples of the materials which constitute the dam. As a result, a greatly decreased zone of resistivity (-75%) was confirmed in the rock material in the upstream side after filling. In addition, the zone of the resistivity change from 5% to -20% was widely distributed in the core and the rock material in the downstream side. Furthermore, the resistivity of the samples of dam materials decreased to -80% when the water saturation was increased from 20% to 100% in the laboratory tests. These results suggest that water saturation in the dam during filling can be visualized by utilizing the resistivity change. In conclusion, electrical exploration is an effective method to monitor penetration during filling of the dam, and to evaluate the safety of the dam's water sealing performance in the event of large earthquakes. |
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