Effect of fine content on asphalt concrete core-transition layer interface shear behaviour

An asphalt concrete core wall is placed between transition layers of asphalt concrete core rockfill dam. The interface between the core wall and the transition layer is subjected to shear action due to lateral soil pressure, water load and varying material properties, which threaten the safety of the core wall. In this paper, the influence of the fine particle content in the transition layer on the shear behaviour of the interface is investigated. A series of shear tests is conducted on the interface between the asphalt concrete and the transition layer of coarse-grained soil under conditions of three fines contents, three shear rates and five normal stress levels. The shear behaviour and shear mechanism of the interface are analysed. The influence of fine particle content on the shear behaviour is discussed. A nuclear magnetic resonance imaging system is used to detect the pore distribution of an asphalt concrete sample after the shear action. Furthermore, a high-pressure permeability test is conducted to study the impact of shear action on asphalt concrete impermeability. The results indicate that shear stress and normal displacement of the interface increase with the fine particle content. The porosity and permeability of asphalt concrete after shear action increases with the decrease of fine particle content. Shear action would not significantly affect the anti-seepage performance of the asphalt concrete.