Influence of Density and Pressure on Spontaneous Shear Band Formations in Granular Materials

摘要

The aim of the present paper is to investigate the possibility of a spontaneous shear band formation in rate-independent, cohesionless and dry granular materials based on a hypoplastic constitutive model. Since the constitutive equation is incrementally non-linear the question as to whether the velocity gradient on either side of the discontinuity is related to loading, unloading or to a rigid body motion is irrelevant for the bifurcation analysis. By including a pressure dependent relative density the hypoplastic model describes the essential properties of initially dense and initially loose granular materials for a wide range of pressures. Thus, the influence of density and pressure on the stress ratio at the onset of a shear band localisation and the corresponding shear band orientation can be investigated with a single set of constitutive constants.