INCREMENTAL STRESS-STRAIN BEHAVIOR OF GRANULAR SOIL

Essential to the development of rate-type, elastoplastic constitutive models to describe the stress-strain behavior of any soil is knowledge concerning magnitude and direction of plastic strain upon application of an incremental stress. A series of stress-probe experiments are performed on a granular material with the objective of developing some understanding of these aspects. Triaxial sand specimens, loaded initially to different specified states of stress, are subjected to incremental stress probing in different directions, and the corresponding strain responses are measured. The results indicate that while the behavior approximately conforms to the theory of plasticity for stress states close to the failure line, it deviates from it for stress states close to the isotropic axis.