Shear behavior of asphalt concrete core and transition layer interface under original gradation condition

Asphalt concrete core wall bears anti-seepage task of asphalt concrete core wall rockfill dam. The core wall is supported by the rockfill body, which plays a decisive role in dam safety. The behavior of interface between the core wall and transition layer is decisive factor affecting the reliability of the core wall structure. It is particularly important to study the mechanical behavior of the interface. This paper studied shear behavior of interface between asphalt concrete core wall and transition layer under original gradation condition. The strength and deformation behaviors of the interface were tested by stacked ring shear test under four different normal stress conditions. On this basis, effect of shear action on the pore structure of the asphalt concrete was investigated by nuclear magnetic resonance equipment. Meanwhile, the effect of shear action on the particles breakage of the transition layer material was discussed on the basis of relative breakage rate and relative breakage parameter indexes. The results indicated that the interface exhibited shear hardening phenomenon under different normal stress conditions. The shear strain increased with the increase of normal stress. The shear action resulted in remarkable growth of small pores under low normal stress conditions. However, the shear action resulted in remarkable growth of medium and large pores under high normal stress conditions. The porosity increased with the increase of the normal stress. However, the porosity of the asphalt concrete after shear action was still within the allowable range of the project control requirements. The particle breakage amount of transition layer material increased with the increase of normal stress. But the particle breakage effect caused by the interface shear action was unremarkable.