Constitutive Modeling for Transparent Granular Soils

Transparent granular soil was recently found to be greatly useful for observations of the internal deformation in geotechnical model tests. Therefore, it is necessary to investigate the stress-strain and stress-dilatancy behaviors of transparent granular soil and also to propose a constitutive model for this material. In this study, drained triaxial shearing tests were conducted to investigate the stress-strain and stress- dilatancy relations of transparent granular soil. It was found that this material showed a state-dependent stress-strain behavior similar to that of sands. A state-dependent constitutive model within the framework of the critical-state theory was proposed to describe the stress-strain and stress-dilatancy behaviors of this material. This model was found to well describe the stress-strain behaviors (e.g., strain softening and volumetric expansion) and the hook-shaped stress-dilatancy behaviors from the test data in both the Group A (for the calibration of material constants) and Group B (for the validation of model predictions) tests. In addition, this model was found to well capture the changes of the peakstate strength, peak-state dilatancy and peak-state strains with the state parameter