Mechanical Properties and Constitutive Model Optimization of Rockfill Materials for CFRD with Deep Overburden Layer

Abstract

: Computer modeling and numerical calculation of concrete face rockfill dams (CFRDs) with deep overburden layers remains challenging because the mechanical response of rockfill materials is highly nonlinear, pressure-dependent, and influenced by particle breakage. To improve the predictive capability of such simulations, this paper develops a nonlinear constitutive model that incorporates a dynamic failure ratio, the spatially mobilized plane criterion, and particle breakage, and establishes a calibration procedure for its numerical implementation. Large-scale consolidated-drained triaxial tests were conducted on three gradations under five confining pressures ranging from 200 to 1000 kPa. The peak deviatoric stress increased with confining pressure, whereas the peak friction angle decreased, and the specimens exhibited contraction followed by dilatancy, particularly at 200–600 kPa. The calibrated model was implemented in a finite-difference computational framework. The framework was applied to the Jinchuan CFRD using an engineering-scale numerical model. The computed maximum settlement was 84.8 cm at approximately 0.25 times the dam height, the maximum horizontal displacement was 15.874 cm (0.13% of the dam height), and the maximum and minimum principal stresses were 1.76 and 0.63 MPa, respectively. The simulated settlement trends generally agreed with field monitoring data. These results demonstrate that the proposed constitutive model can capture the nonlinear mechanical response of rockfill materials and provide a practical numerical tool for the analysis and