A Biorthogonal Laser Plane Based DIC Measurement and Reconstruction Method for 3-D Deformation of Transparent Soil

ABSTRACT Transparent soil model testing (TSMT) is emerging as a popular geotechnical testing technique. However, measuring 3-D soil deformation in TSMT remains a challenge. To address this difficulty, this study investigated a new approach to improve efficiency for out-of-plane displacements measurement. The core idea was to add another set camera and laser perpendicular to the directions of the camera and laser in the conventional TSMT apparatus. Images of multiple orthogonal sections of soil were captured with the aid of a synchronous stepping device. Digital image correlation technique was used for image processing to get displacements of each soil section. Subsequently, custom MATLAB codes were programmed to reconstruct and visualize the 3-D deformation field based on the calculated displacement data of individual soil sections. By way of example, the proposed approach was applied to three soil penetration problems: the piezocone, T-bar, and ball penetrometers. Coupled Eulerian-Lagrangian finite element method was used to simulate the tests. Through comparison between FEM and test results, the soil had consistent deformation patterns. It demonstrated the reliability of the proposed method and the valuable geomechanical insights that could be achieved by tracking internal 3-D soil deformations.