To prevent the loss of fine particles from the core walls of earth dams, filter layers with filtration and drainage functions are typically installed behind the core wall. These filter layers are crucial for ensuring the safe operation of earth dams. This study conducted seepage experiments using transparent soil to investigate the effectiveness of filter layers in preventing erosion. Special attention was given to the soil-structural interface to assess its impact on erosion and clogging phenomena. The results indicate a boundary effect on the erosion and clogging of fine particles: fine particles near the structural interface are lost in the early stages of seepage due to the larger porosity at the boundary. Some of the lost particles move vertically upward along the boundary and flow out of the soil, while some flow with the fluid into the soil and become clogged within it. Consequently, there is less clogging near the structural interface and more clogging inside the soil.