ABSTRACT
The phenomenon whereby only the fine soil particles flow out, while the skeleton of the coarse soil particles remains, is called “suffusion”. It has been pointed out that the suffusion occurs in embankment structures affected by long-term seepage, such as river levees and reservoir dams, increasing the risk of collapse. However, the suffusion mechanisms in cases where the seepage force changes with time are often unclear. In this study, water-passing experiments with the suffusion were performed to clarify how the amount and the particle size of eroded soil change with changes in the seepage force. As a result, it was seen that the small soil particles with easy flowability had already eroded when the specimen was subjected to seepage force for the first time, and that the soil particles that flowed out due to changes in the hydraulic gradient were relatively large in diameter.
