Investigation of Nonuniform Creep Behavior and Crest Cracking of an Asphalt–Concrete Core Rockfill Dam After Reservoir Impoundment

ABSTRACT Variations in environmental humidity induce changes in the moisture content of rockfill materials, thereby influencing their creep behavior. In core rockfill dams, reservoir impoundment alters the environmental humidity conditions of the upstream rockfill materials, which often induces nonuniform creep deformation between the upstream and downstream zones. Excessive nonuniform creep deformation may lead to structural damage of the dam during its subsequent operation. This study presents an in‐depth analysis of the impact of nonuniform creep deformation following reservoir impoundment on the long‐term safety of an asphalt–concrete core dam exhibiting pre‐existing crest cracks. To this end, a classical empirical creep model was modified to incorporate the humidity‐dependent creep behavior of rockfill materials and subsequently integrated into a finite‐element program for numerical analysis. Model parameters used in the modified creep model were identified using on‐site monitoring data through the backpropagation‐particle swarm optimization inversion method. The good agreement between the calculated results and existing monitoring data indicates the validity of the proposed numerical simulation scheme. Based on the simulation results, a thorough discussion is presented to clarify the causes of crest cracking and evaluate the safety of the dam. Stress analysis of the core crest pavement reveals that differential saturation levels on either side of the core wall induce tensile stresses in the pavement, which lead to cracking. Further stress analysis of the core wall suggests a low probability of cracking or hydraulic fracturing. Meanwhile, predictive deformation analyses indicate that creep deformation is expected to stabilize approximately 4 years after impoundment.