During the operational phase of pumped storage hydropower stations, rockfill materials within the dam experience cyclic loading and unloading due to water level fluctuations. This cyclic behavior can result in the accumulation of irreversible deformation, posing a substantial threat to dam safety. However, there is an absence of a constitutive model capable of accurately capturing the low-frequency multi-cycle hysteresis behavior of rockfill materials due to the constraints of conventional laboratory test methods. In this study, we employed the combined finite and discrete element method (FDEM) to investigate the mechanical characteristics of rockfill materials and develop an improved constitutive model capable of effectively capturing their hysteretic behavior. The results demonstrate the FDEM accurately reproduces the mechanical behavior of rockfill material under shear and cyclic loading and unloading conditions. The hysteresis loop exhibits a discernible densification trend with increasing cycles. And the variations in elastic modulus and strain primarily occur within the initial five cycles. The plastic strain increment exhibits a strong positive correlation with stress level, while its relationship with confining pressure is comparatively less pronounced. The proposed constitutive model successfully captures the complex low-frequency multi-cycle hysteresis characteristics of rockfill material with few parameters, showing substantial potential for practical applications.

来源平台：COMPUTERS AND GEOTECHNICS