| 講演要旨(和文) | | 北海道中部の千歳川では樋門設置のための堤防開削が行われた．スリングラム電磁法，高密度比抵抗法電気探査，表面波探査を天端および高水敷で開削前に実施した．この探査により，堤体はほぼ層構造であるが，その基礎地盤は複雑な構造であることが示された。開削後，開削斜面表面で比抵抗値やS波速度を直接測定した．比抵抗値，S波速度と開削面で採取された土質試料に対する粒度や透水係数を比較したところ，堤防内の高透水ゾーンの比抵抗値やS波速度が確認された．堤防を横切る電気探査により，基礎地盤に延びる高透水ゾーンや堤体および基礎地盤の不均質性が明らかにされた． |
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| | 講演要旨(英文) | | A levee excavation was conducted to construct a new sluice at two sites along Chitose River, Central Hokkaido. The slingram EM, the high-density electrical resistivity survey and the surface wave survey were carried out at the crown of levee and high-water channel before the excavation. These survey delineated layer structure in the levee and complex structure in its basement layer. After the excavation, the resitivity mapping and the short spacing surface wave survey were carried out at the excavated slope surface to measure directly resistivity and S wave velocity (Vs) on the surface. Comparing resistivity, Vs with grain size and perameability for sampled soils, we identified resistivity and Vs of permeable zone in the levee. The electrical resistivity survey across the levee delineated extension of the permeable zone to the basement and imhomogeneity in the levee and its basement. |
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