Experimental Investigation of Internal Erosion Behaviors in Inclined
Seepage Flow
Abstract
Internal erosion is one of the most common causes of failure in
hydraulic engineering structures, such as embankments and levees. It
also plays a vital role in the geohazards (such as landslides and
sinkhole developments) and more importantly, the earth landscape
evolution, which has a broad environmental and ecosystem impacts. The
groundwater seepage is multi-directional, and its multi-dimensional
nature could affect the initiation and the progression of internal
erosion. With a newly developed apparatus, we carry out nine internal
erosion experiments under five different seepage directions. The results
reveal that the critical hydraulic gradient increases as the seepage
direction varies from the horizontal to the vertical. After a global
erosion is triggered, preferential erosion paths distribute randomly
from the bottom to the top of the specimen. If the seepage direction is
not vertical, small preferential erosion paths merge into a large
erosion corridor, in which the loss of fine particles is significant but
negligible outside. Results of experiments manifest that the erosion is
heterogeneous and three-dimensional, even in the unidirectional seepage
flow. The particles are rapidly eroded at the early stage of the
erosion, indicating a high erosion rate. With the erosion time
increasing, the particle loss slows down and even ceases if the time is
long enough. The erosion rate increases if the seepage direction
approaches a vertical direction. Overall, the erosion rate approximately
decreases with erosion time exponentially. We proposed exponential
equations to illustrate the variation of the erosion rate in the erosion
process.