| 講演要旨(和文) | | 越流発生時の河川堤防の挙動を観察することを目的に、約5分の1のスケールの小型模擬堤防を用いて越水現象の実験を行った。これに伴う観測項目のひとつとして3次元比抵抗モニタリングを行った結果について報告する。越水実験では堤防表側に貯水池を設けて庄内川より河川水を汲み上げて水位を制御し、小型堤防へ外水位の負荷と散水装置による人工降雨を与えた。比抵抗の測定では、小型堤防全体をカバーできるよう8測線で合計3072データの測定を一定の時間間隔で繰り返した。測定では、時間間隔をできるだけ短縮するために電流送信器を8台・電位測定器8台の多点同時通電システムを用いて約20分間隔で一連の測定を繰り返した。3次元比抵抗モニタリングの結果、人工降雨や外水位上昇に伴う堤体内の比抵抗変化を明瞭に捉えることが出来た。 |
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| | 講演要旨(英文) | | We conducted a field experiment of 3D ERT monitoring during a simulation of levee overflowing using a small model bank. We used 1/5 scale model bank and built a water pool for putting outside water level and rising at river levee and overflowing. As one of monitoring measurements while water level rising, we conducted time-lapse 3D ERT measurement on this model bank as a mean of grasping water movement inside the model bank. We applied multi-current transmission technique to realize rapid measurement. By using our instrument based on this technique, which has 8 transmitters and 8 receivers, we could conduct a set of measurement which has 3072 data at the interval of 20 minutes. We performed 2D and 3D resistivity inversion. ERT measurement captured the water infiltration into the model bank by fine time resolution. The brackish saline water worked as a good tracer of ERT measurement in this case. 3D inversion using 2D survey lines data contributed to understand the spatial distribution of resistivity time variation. |
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