<p>Ensuring the seismic resilience of embankment dams requires a thorough understanding of the dynamic behaviour of dam filter materials under cyclic loading. This study investigates the combined influence of particle sphericity and loading waveform on the shear modulus and damping characteristics of cohesionless granular filter materials through a combined experimental–numerical approach. Sand obtained from the Haraz Dam filter zone was classified into high-, medium-, and low-sphericity groups using image-based measurements of sphericity, roundness, and aspect ratio. To isolate particle-shape effects, specimens were reconstructed with the same grain-size distribution for all shape groups. Cyclic triaxial tests were first conducted under sinusoidal loading at different void ratios and confining pressures. A discrete element model using PFC3D was then calibrated against the experimental results and used as a validated particle-scale tool to investigate the response under sinusoidal, triangular, and rectangular loading waveforms. The results show that the effect of loading waveform depends strongly on particle morphology. Low-sphericity particles exhibited greater sensitivity to cyclic loading, with modulus degradation reaching about 40% at 0.5% shear strain, compared with about 25% for high-sphericity particles. Rectangular loading produced the highest shear modulus, reaching approximately 120&#xa0;MPa at 0.1% shear strain, and generated stronger contact-force transmission, higher coordination numbers, and larger particle displacements, particularly in low-sphericity assemblies. These findings provide new insight into how waveform modifies the shape-dependent dynamic response of dam filter materials and offer a more realistic basis for seismic assessment and design of embankment dam filters.</p> Graphical abstract <p></p>