Stability of sandy soils against internal erosion under cyclic loading and quantitatively examination of the composition and origin of eroded particles

Abstract

Existing criteria for assessing internal erosion usually are based on static loading and the effect of cyclic load is not considered. Additionally, there are limited studies to examine the particle-size destitution and origin of eroded fine particles. This work presents an experimental investigation that examines the impact of cyclic loading on internal stability through a series of seepage tests. The composition and origin of lost particles are quantitatively studied using particle staining and image recognition techniques. After significant loss of particles, the specimens reach a state of transient equilibrium, resulting in a gradual slowdown of both particle loss rate and average flow velocity. The results indicate that cyclic loading promotes massive particle loss and causes erosion failure of specimens that are considered stable according to existing criteria. The reason is that under cyclic loading, local hydraulic gradients is oscillating, and a larger than average hydraulic gradient may occur, which is responsible for the internal instability. The analysis suggests that existing criteria can provide a reasonable assessment of the relative stabilities of specimens under static loads, but fail to capture the stabilities under cyclic loading conditions.