ABSTRACT
Internal erosion is responsible for an overwhelming proportion of dam failures. The microstructure of soil and its mechanical properties can be affected by particle migration, resulting in a decrease in soil stability. Using a modified erosion testing apparatus, this research examines the impact of internal erosion on the small strain shear modulus (G0) of gap-graded granular soils. The moist tamping technique was used to prepare internally unstable gap-graded soils with varying fines content and relative densities. The specimens were subjected to a downward seepage flow, while the induced pore pressure and erosion progress both monitored continuously. Three sets of bender elements were mounted on the cell to track the variation in shear wave velocity throughout the sample height during erosion. The results indicate the negative correlation between fine particle content and G0, while suggesting that the increment of soil compaction would potentially accelerate G0 at transitionally unstable zone.
