Title: A Generalized Critical State Approach for Granular Rheology and Impact Loading
Abstract: The dynamics of dense granular-fluid mixtures, such as those occurring in landslides and debris flows, embody a complex interplay and transition between solid mechanics and fluid dynamics. Despite major advances in large-deformation analysis, geotechnical modeling remains largely governed by strain-independent critical state soil mechanics, even though substantial evidence indicates that granular rheologies more accurately describe the constitutive behavior of materials undergoing flow and large strains.
In this seminar, I will present a constitutive framework that extends the critical state concept by incorporating principles from particle kinetic theory and granular rheology. This generalized critical state formulation captures the continuum of granular behavior beyond the solid and dense flow regimes. Using numerical simulations of impact triaxial tests, the framework successfully predicts enhanced peak deviatoric stresses and pronounced dilation at small strains under high-velocity impact loading. These results demonstrate the potential of extended critical state models to describe strain-rate–dependent rheologies and hydromechanical coupling in granular-fluid mixtures.