Effect of Valley Topography on the Behavior of Asphalt Concrete Core Walls in Earthen Dams

An increasing number of asphalt concrete core wall earthen dams (ACCDs) are being constructed under complex topographical conditions. The narrow or asymmetrical river valleys might lead to significant arching effects and excessive shear deformations in the core walls, which affect structural safety. This paper focuses on the effect of valley topography on the behavior of asphalt concrete core walls in earthen dams with numerical analysis. The nonlinear behavior of asphalt concrete and rockfill materials is described using the Duncan–Zhang E–B model. The contact behavior between the core wall and transition layer is described by the Goodman contact surface model. Six parametric three-dimensional (3D) finite-element models with different valley topographies are established based on the Jiangjiakou (Bazhong City, Sichuan Province, China) ACCD and the statistical analysis of the valley topography. The effects of valley width, slope steepness, and asymmetry on the behavior of the asphalt concrete core wall are discussed. Compared with wide valleys, the stresses and displacements in the core walls in narrow valleys are relatively smaller. However, significant arching effects are observed in the upper-middle portion of the core walls. The tensile and shear stresses on both sides of the core wall in a steep-sloped valley are significantly larger than the core wall in a gentle-sloped valley. Uneven deformations are evident in the core walls in the asymmetric valley, which leads to large axial tensile strains in the core wall.