Evaluation of Load Transfer in Geogrids for Base Stabilization Using Transparent Soil

The design of roadways with geosynthetic-stabilized base layers requires proper evaluation of the load-transfer mechanisms between soil particles and geosynthetics. In the case of geogrid reinforcements, the resistances mobilized on rib elements are key factors that determine the mechanical responses for both: (1) the ultimate pullout strength; and (2) the in-plane stiffness. Geogrids with different aperture shapes have rib elements along different orientations, and different rib orientations could generate different load transfer mechanisms. In this study, a new experimental testing program using transparent soil was conducted to visualize the load transfer of geogrids with different aperture shapes (e.g. rectangular, triangular). Specifically, small-scale soil-geosynthetic interaction tests were conducted using high-definition cameras. Consequently, image-processing techniques were used to obtain the displacements and deformations of geogrid specimens from digital images. The soil-geogrid interaction behaviors for geogrid specimens with different aperture shapes were evaluated and compared. Overall, multiple mechanisms for load transfer between soil and geogrids with different geometric characteristics could be characterized and quantified using new techniques involving transparent soil and digital image analysis.