Constitutive modeling of sand: Formulation of a new plasticity approach

•Constitutive modeling of sand: a new plasticity approach.•Critical state consistency for monotonic and cyclic loading.•Novel plastic flow rule for anisotropic distribution of dilatancy.•Hardening and mapping rule based on Bouc–Wen type smooth hysteresis.•Flexibility to reproduce liquefaction at very large cyclic shear strains.

A constitutive model for sand is derived based on a new theoretical framework that combines features of perfect elastoplasticity and smooth hysteresis. It resembles a bounding surface model with vanished elastic region, but with considerable modifications in that the plastic modulus is not explicitly defined, and the mapping rule is Bouc–Wen motivated and works equally well in monotonic as in stress-reversal loading. Among the proposed features, are: (a) critical state compatibility not only for monotonic but also for cyclic loading, and (b) novel plastic flow rule accounting for anisotropic distribution of the dilatancy strain ratio, d, to the normal plastic strain increments. The capability of the model in capturing complex aspects of sand behavior (e.g. cyclic mobility, static liquefaction, densification) is demonstrated through illustrative paradigms with emphasis on the physical meaning of each key-model parameter and comparisons with experimental data.