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| Abstract | In-situ detailed geophysical measurements and laboratory geotechnical analysis have been systematically conducted at excavated sites as for the ground truthing or the verification of the result of integrated geophysical surveying conducted on levee systems before excavation. Resistivity mapping on dense grid points and high-frequency surface wave surveying along short lines set on the excavated surfaces were the major geophysical techniques in the field. A 10 cm spacing Wenner type electrode array was used to estimate the apparent resistivities at the points assuming half-space homogeneous structure. S-wave velocities at the corresponding points were calculated by averaging values for surficial 40 cm portion along the line. The laboratory geotechnical analyses consisted of specific grain size characteristics (D20 and Fc), and water contents. Dataset more than 500 pairs of the field and laboratory data were correlated with each other to clarify the relationship between them. A clear relationship was identified between resistivity and the specific grain size characteristics whereas the water contents varied and the specimens were unsaturated. In contrast, S-wave velocities showed a low relationship with the laboratory data, presumed to be influenced of loosening by excavation. |
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