Strength-Deformation Behavior of Sandy Soil with Different Structures: Layered Structure Versus Uniform Structure

The strength and deformation characteristics of sandy soils are influenced by sedimentary conditions such as grain orientation, void ratio, and heterogeneity of grain size distribution. In this study, random and organized heterogeneity of grain size distribution is investigated in a series of laboratory experiments. Triaxial compression tests were performed on sandy soils with a layered structure, which were identified according to the segregated size of grains and uniform structure packed with the mixed size particles. Moreover, X-ray computed tomography (CT) scans of the specimens are acquired during the loading phase to observe their local deformation behavior. For tests with a layered structure, a more dilative behavior and a higher shear strength were observed compared to tests with a uniform structure. The results of image analysis from CT images indicate that the more dilative response for the layered structure occurred predominantly in the largest particle sublayers and at the boundaries between adjacent sublayers.