Effects of Internal Erosion on Levee Instability

Daily precipitation in Japan is currently increasing. River levees are constructed by compacting various natural materials. Internal erosion can be induced by suffusion, in which fines within the soil skeleton are transported to the toe of levee or outside the levee in an accordance with seepage flow. There are very few studies that refer to the effects of internal erosion on macro deformation and the instability of a levee. In this study, modeling tests of a levee were carried out to simulated floods in a 30g centrifugal field. Two types of material were prepared based on Kenny’s diagram, one classified as “stable” and the other as “unstable”. For stable soil, surface erosion could be observed on the landside of the levee. When the flood level was increased to overtop the crest, the levee caused catastrophic failure. Whereas, for unstable soil, tension failure was observed the toe, whereby, catastrophic larger circular slip was able to be confirmed.