Influence of aggregate particle size on fracture behavior and energy evolution of cemented rockfill in the post-peak stage

• Finer aggregate gradation increases compressive strength, elastic modulus, and post-peak stiffness of cemented rockfill. • Fracture patterns shift from unidirectional to X-shaped conjugate shear as aggregate size decreases, with cracks initiating at boundaries. • Finer gradation produces a more homogeneous crack network, enhancing post-peak load retention and causing frequent minor stress fluctuations. • Although cumulative energy dissipation is highest for coarse aggregates, finer aggregates delay rapid energy release, promoting slower redistribution and improved load resistance.