An elastoplastic three-surface model for simulating particle breakage and cumulative deformation of granular soils under monotonic and high-cycle loads

Particle breakage often occurs when granular soils are subjected to monotonic and cyclic loads, which significantly affects their mechanical behavior. However, constitutive models that consider the evolution of particle breakage and cumulative deformation in granular soils under high-cycle loads remain limited. To address this gap, this study develops a constitutive model for granular soils under monotonic and high-cycle loads. Firstly, an approach is proposed to phenomenologically decouple the interactive effects between particle rearrangement and particle breakage in granular soils. Following this approach, the plastic volumetric strain is decomposed into particle rearranging and particle crushing components. By defining a coefficient of particle crushing potential and introducing it into an existing stress-dilatancy-breakage energy equation, these two components can be quantitatively evaluated. Secondly, a unified expression is proposed to control the evolution of the particle crushing potential as loading and particle crushing progress. Thirdly, the decoupling approach is integrated into the frameworks of critical state soil mechanics and bounding surface plasticity, and an elastoplastic three-surface model is formulated. The model involves a loading surface, a bounding surface, a memory surface, and their evolution rules are elaborately designed in stress space. The memory surface plays a role in reproducing the transition of the hysteretic stress–strain relations from ratcheting to shakedown. Finally, the three-surface model is validated by simulating some laboratory tests conducted on three granular soils, including cases involving up to 100,000 loading cycles. The comparisons with experimental data demonstrate that the model is capable of simulating the evolution of particle breakage and evaluating its influence on the cumulative deformation of granular soils under monotonic and high-cycle loads.