An Experimental Study on the Effect of Soil-Structure Interface on the Occurrence of Internal Erosion

Abstract

Internal erosion affects the stability of embankment dams and other earthen structures, and usually develops at the interface of multiple layer surfaces with different particle sizes. It is characterized by weak areas formed in the embankments around water sluices and pressure conduits. This study presents the phenomenon of internal erosion aided by lab experimentations. Permeability and particle size distribution tests were performed under varying characteristics of the soil-structure interface. Weak zone development in a structure with fine soil particles and vulnerable to displacement was a function of the flow velocity of the water. Surface roughness at the interface adds to the displacement potential of fine particles. The smooth surface interface helps increase the flow velocities, thereby enhancing the rate of internal erosion. Loss of fine particles at the interface helps significantly increase erosion, especially at the boundary, resulting in intense erosive action. A significant difference was observed between the erosion potential of rough and smooth concrete structures and the soil for nearly half of the total area of the sample, which was eroded in both cases. The variation of velocity is mainly seen at the embedded structure’s interface in the soil, and remained constant around the other regions of the soil sample, indicating no specific impact. The erosion of the soil particles was mainly dependent on the distance from the soil-structure interface.