FULL-FIELD DEFORMATION MEASUREMENT OF SAND USING THE DIGITAL IMAGE CORRELATION TECHNIQUE AND NUMERICAL SIMULATION USING THE DISCRETE ELEMENT METHOD

Geotechnical materials are characterized of anisotropy and nonlinearity. Different composition leads to different deformation in soil. In order to measure the actual deformation of soil in the plane strain condition, a new plane strain testing apparatus was used to apply flexible pressure to the lateral sides of specimens. Unlike rigid loading, this loading method reduces the influence of boundary constraints. At the same time, a digital image measuring system was combined with this apparatus to obtain the surface deformation of specimens. The 2D digital image correlation (2D-DIC) technique was used to measure the full-field deformation of Fujian (China) sand in different confining pressures. In addition, microscopic parameters of the rolling resistance linear model in the discrete element method (DEM) were calibrated by using the experimental results, and the experiments were simulated by using DEM. Results show that the new plane stain testing apparatus combined with the 2D-DIC technique can not only obtain the local deformation distribution of Fujian (China) sand but also obtain the asymmetric deformation directly. Furthermore, the calibrated microscopic parameters can truly represent the stress-strain relationship of the tested specimens.