Multiscale modelling reveals new insights into the deformation mechanism of rockfill dams

Dams are among the most critical structures in hydraulic engineering, where stability and deformation analysis are essential for ensuring structural safety. For rockfill dams, especially those exceeding 200 m, accurately predicting deformation and settlement remains a significant challenge. This limitation arises from the shortage of conventional constitutive models to fully capture the complex mechanical behavior of rockfill materials, including nonlinear stress–strain response, scale effect and particle breakage, etc. In this study, a hierarchical multiscale approach is introduced to address these challenges. The proposed method significantly improves upon the limitations of earlier multiscale simulations by utilizing high-performance parallel computing. A three-dimensional numerical model of a 233-meter-high prototype dam is developed, which can simulate at the scale of hundreds of millions of particles and provide valuable insights into the deformation mechanism of dams at the particle scale. The micromechanical parameters of RVEs are calibrated using results from laboratory triaxial tests. The simulated deformations from the multiscale model are closely consistent with the monitoring data, validating the accuracy of the proposed method. Through comparative analysis with FEM simulations using the Duncan-Chang constitutive model, new insights were gained, revealing the critical need to account for true triaxial stress states at the dam crest and the upstream and downstream slopes. Additionally, the multiscale simulation quantified the spatial extent and magnitude of deformation caused by particle breakage, providing a more comprehensive understanding of the role of particle-scale mechanical evolution in the macro-scale behavior of rockfill dams. These findings underscore the importance of considering both macro and micro-mechanical behaviors for accurate safety assessments and deformation predictions in rockfill dams.