SEGJ Technical Conference

Geophysical surveys in levee excavation sites along Chitose River

Abstract 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.