Canadian Geotechnical Journal, Ahead of Print.
Internal erosion refers to the movement of fine particles within soil framework due to subsurface water seepage. 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 distribution and origin of eroded fine particles. This study 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. With increasing hydraulic gradient, particle erosion progresses from top layer to bottom layer, with a gradual increase in the maximum particle size of eroded particles from each layer. 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.

中文翻译：

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循环荷载下沙土抗内侵蚀的稳定性及侵蚀颗粒成分和来源的定量检测

加拿大岩土工程杂志，印刷前。
内部侵蚀是指由于地下水渗漏而导致细颗粒在土壤框架内的移动。现有的内腐蚀评估标准通常基于静载荷，没有考虑循环载荷的影响。此外，检查侵蚀细颗粒的粒径分布和来源的研究也很有限。本研究提出了一项实验研究，通过一系列渗流测试来检验循环荷载对内部稳定性的影响。使用颗粒染色和图像识别技术定量研究丢失颗粒的组成和来源。随着水力梯度的增大，颗粒侵蚀从顶层向底层进行，各层侵蚀颗粒的最大粒径逐渐增大。颗粒大量损失后，样本达到瞬态平衡状态，导致颗粒损失率和平均流速逐渐减慢。结果表明，循环加载会促进大量颗粒损失，并导致根据现有标准被认为是稳定的样本发生侵蚀破坏。原因是在循环加载下，局部水力梯度发生振荡，可能会出现大于平均水力梯度，这是造成内部不稳定的原因。分析表明，现有标准可以对静载荷下样本的相对稳定性进行合理评估，但无法捕获循环载荷条件下的稳定性。