Bounding surface model refined with fractional dilatancy relation for sand

Abstract

Due to its simplicity, the Sanisand bounding surface model was developed for constitutive modelling of sand, which has been widely used. Nevertheless, the model ignored the dependence of yielding on Lode’s angle, sometimes showed a concave plastic potential surface, and had several parameters that required simultaneous identification through trial and error, which could affect model performance. This study aims to refine the model by providing alternative multiaxial yielding and dilatancy relations. This is possible through the definitions of a modified yielding function and fractional stress–dilatancy ratio enriched by fabric-dilatancy tensor. This approach can enhance the model performance and simplify the calibration process. The refined model can simulate various stress paths, stress–strain hysteric loop, unloading-induced contraction, reloading-induced dilatancy, butterfly-shaped liquefaction, etc., of different sands.

Keywords

• Lode’s angle
• Stress-dilatancy
• Fractional order
• Fabric-dilatancy tensor
• Sand