In geotechnical engineering, understanding the mechanisms of deformation and failure of granular materials is essential. For detailed analysis, both macro and microscale conditions should be considered; however, geotechnical analysis methods that can handle the microscale condition are not sufficiently developed. In experimental studies, quantitative evaluation of deformation and failure behavior from micro to macroscale can be achieved through full-field measurements of displacement and strain fields in soil specimens under load. In the present study, in-situ triaxial compression tests on sand that allow simultaneous loading and X-ray scanning were performed. In addition, 3D displacement and strain field analysis and 3D grain tracking were conducted based on X-ray CT data. A geotechnical analysis method that utilizes this method may be considered effective. Moreover, the author propose a finite element (FE) analysis method that considers the microscale condition of granular materials using X-ray CT data. The FE analysis is implemented with particle discretization, and both mesh size and geometry are determined from X-ray CT data. Particle Discretization Scheme (PDS)-FEM is used for numerical simulation of failure behavior. As a result of the numerical analysis, a series of results for the triaxial compression test on sand is discussed. Laboratory test results are compared with simulation results, and the validation of the proposed model is discussed.

Key Words: Granular materials, Sand, Triaxial compression test, X-ray tomography, Image analysis, Particle discretization, Finite element method