A 2-D constitutive model for cyclic interface behaviour

The paper concerns a 2-D constitutive model for interface behaviour between sand and solid inclusionsunder cyclic loading. The model is based on the experimental results obtained from laboratory direct shearinterface tests conducted under both constant normal load (CNL) and constant normal stiffness (CNS)conditions. The model is formulated in terms of interface stresses and relative velocities and has beenderived by extending an elastoplastic isotropic model previously formulated for monotonic loading tostress reversal paths. Such extension consists in adding to the isotropic hardening mechanism a kinematicrotational one defined by an inner conical surface rotating around the origin of the stress space. This allowsone to store the memory of the previous stress and relative displacement history giving to the model thecapability to analyse the interface behaviour under cyclic loading. After a brief description of the criteriagoverning the monotonic model, the paper describes in detail the features of the kinematic hardening.Finally, the predictions of the model are compared with the experimental results obtained from CNL andCNS interface tests.