Advanced Imaging Techniques for Soil-Structure Interaction Problems

Advanced imaging techniques have gained popularity in geotechnical research for resolving soil deformation fields in a variety of soil-structure interaction problems. The main advantages of these techniques over conventional methods are: (1) they provide non-intrusive continuous measurement of soil deformation, and (2) they allow multiscale observations of granular media behavior from meso scale digital image correlation (DIC) analysis to micro scale grain level kinematics. These advantages have opened up more avenues to investigate important aspects of collective behavior in granular media such as formation of force chains and shear localization, all of which are important to deepen our understanding of soil-structure interaction problems.;In this dissertation, algorithms to describe meso and micro scale kinematics of granular flow using advanced imaging techniques are described. At the meso scale, first, a critical evaluation of the various methods and components of DIC relevant to geotechnical applications are presented. Second, new algorithms are developed to address some specific problems encountered when using DIC techniques in geotechnical research. Third, the finite strain method is implemented to calculate rigid body rotation, shear and volumetric strain based on obtained DIC displacement fields. Fourth, codes are developed to construct both Eulerian and Lagrangian trajectories of soil elements from incremental DIC analysis results. Fifth, stereo DIC has been introduced to obtain 3D soil deformation in a given plane. At the micro scale, individual particle kinematics is resolved using particle identification, tracking and rotation algorithms. Micro scale analysis of kinematics is performed using definitions of affine and non-affine local motion.;These advanced imaging techniques have been applied and proposed to investigate four soil-structure interaction problems. First, the meso-scale processes occurring during projectile penetration into sand were investigated using DIC. Second, the behavior of granular media around a driven pile was explored using both DIC and particle kinematic analysis techniques. Third, the behavior of the assemblies of dual-sized plastic circular rods in a plane strain chamber subjected to toe rotation was investigated using particle kinematics analysis tools. Fourth, a stereo DIC technique was proposed to study the 3D distribution of ground settlement due to construction of a tunnel. The successful results obtained from these investigations have demonstrated the capability, the effectiveness and the potential of applying these advanced imaging techniques to study soil-structure interaction problems.