Local Deformation Analysis of a Sand Specimen Using 3D Digital Image Correlation for the Calibration of a Simple Elasto-Plastic Model

The use of Digital Image Correlation (DIC) technique has become increasingly popular for displacement measurements and for characterizing localized material deformation. In this study, a three-dimensional digital image correlation (3D DIC) analysis was performed to investigate the displacements on the surface of a dense sand specimen during a triaxial compression test (drained, vacuum consolidated). The deformation of a representative volume of the material captured by 3D DIC is used for the estimation of the kinematic and volumetric conditions of the specimen at different stages of deformation, combined with the readings of the global axial compression of the specimen, which allow for the characterization of the Mohr-Coulomb plasticity model with hardening and softening law. A 2D finite element model is developed for comparing the experimental results under displacement controlled loading conditions. A comparison between model predictions and the expected displacement fields show good agreement, as to reproduce accurately the overall mechanical behavior of a dense sand specimen and to take into account the influence of local effects in the mechanical parameters obtained by 3D DIC.