Long-Term Structural Behavior of Concrete Face Rockfill Dams Considering Fluid–Solid Coupling Effects and Spatial Parameter Variability

A numerical method is proposed to analyze the long-term structural behavior of concrete face rockfill dams (CFRDs), considering fluid–solid coupling and the spatial variability of model parameters. Initially, a method was explored for calculating the wetting deformation of rockfill within a CFRD, considering an effective stress framework and fluid–solid coupling. Subsequently, the wetting model was implemented into a FEM subroutine. Next, volumetric and axial creep curves were derived from triaxial creep tests conducted at varying porosities. Based on these test results, an enhanced creep model with higher accuracy was formulated and integrated into a finite-element calculation program. Furthermore, regression models were developed to assess the relationship between rockfill compaction quality and improved creep model parameters. The Particle Swarm Optimization (PSO)-Kriging method was employed to estimate the dam's global compaction quality. Moreover, spatial estimation of improved creep model parameters and refined assignment of FEM parameters were achieved. This refinement led to an enhanced simulation of CFRD, accounting for the wetting effect of dam materials and the spatial variability of model parameters under fluid–solid coupling. Finally, verification using a specific engineering case study demonstrated that the wetting effect of rockfill caused by impoundment and the spatial variability of creep model parameters can substantially enhance calculation accuracy. Consequently, the proposed method significantly contributes to predicting the long-term deformation of CFRD and ensuring the service safety of antiseepage concrete faces. In addition, it provides a more dependable technical method for analyzing the structural performance of CFRDs throughout their entire life cycle.