COMPARISON OF FRICTIONAL MATERIAL MODELS WITH RESPECT TO SHEAR BAND INITIATION

The existing elasto-plastic models of geomaterials have been developed on the basis of experiments in which uniform straining was attempted. The shear bands observed in experiments have been described directly without direct relation to the elasto-plastic models. However, shear band initiation can be considered as an instability of plastic flow; consequently the material behaviour under uniform deformation and the occurrence of a shear band can be considered as coupled phenomena. In this Paper the coupling relations are elaborated and applied in the calculation of shear band initiation for a range of popular constitutive models of materials like drained clay, sand, concrete and rock. It is found that amongst the popular elasto-plastic models large variations in the predicted slope of the shear band and the predicted instant of initiation occur. Les modeles elasto-plastiques des sols existants ont ete developpes sur la base d'essais dans lesquels une deformation uniforme est imposee. La formation des surfa...