Characteristic limitations of advanced plasticity and hypoplasticity models for cyclic loading of sands

Numerous studies in the literature are concerned with proposing new constitutive models for sands to simulate cyclic loading. Despite considerable progress in this area, there are various limitations on their simulation capabilities that are either overlooked or not communicated clearly by the developers. A number of these limitations are rather crucial for the end users, and therefore, providing discussion and analysis of them would be of great value for both applications and future developments. The present work is devoted to discussing seven characteristic limitations, which are frequently observed in cyclic loading simulations. Four advanced constitutive models are considered in this study: two bounding surface elastoplasticity and two hypoplasticity models-with the models in each category following a hierarchical order of complexity. Relevant cyclic loading experimental test data on Toyoura and Karlsruhe fine sands support the analysis. The key issues discussed include stress overshooting, one-way ratcheting in cyclic strain accumulation, liquefaction strength curves, stress attractor in strain-controlled shearing, hypoelasticity, cyclic oedometer stiffness, and effect of drained preloading. The presented results elaborate on the specific limitations and capabilities of these rather advanced models in simulating several essential aspects of cyclic loading of sands.