Bifurcation Analysis of Shear Band for a Cohesive-Frictional Granular Material with DEM-Based Constitutive Model

In classical geomechanics, bifurcation theory and stability analysis are powerful tools for predicting the behaviour of complex system, such as geomaterials. While previous bifurcation analyses have been obtained using classic constitutive models (i.e. non-associated plasticity, hypoplastic or strain-softening plasticity models), in this paper, bifurcation analysis for granular material sample has been carried out with a new DEM-based constitutive model. This new constitutive law has been developed by the author in recent years and has been demonstrated to correctly take into account the discrete nature of granular material. During this work, we focus on the case of biaxial test aiming to discuss the feature of formation of shear band and non-homogeneous deformation of granular sample. Moreover, the onset of the shear band is predicted by the evaluation of the determinant of the acoustic tensor (Rice criterion). We show that the evolution of Rice criterion is in agreement with the future shear band predicted by the simulation. However, the shear band orientation is affected by the geometry of the problem.