ON STRAIN LOCALIZATION AND POST-BIFURCATION RESPONSES IN SOILS

摘要

This paper is concerned with strain localization and post-bifurcation responses in soils. First, localization criteria for soils under plane-strain compression conditions are addressed. Attention is paid to the introduction of a non-coaxial plasticity theory. With this theory, the theoretical predictions for shear band initiation and orientation are shown to be in accordance with experimental observations from plane-strain biaxial tests. Subsequently, in order to simulate the post-bifurcation responses of soils, a homogenisation procedure estimating the average macroscopic behaviour of a soil medium incepted by a shear band is introduced. The formulation presented here is different from the original one proposed earlier by Pietruszczak, which is primarily due to a different choice of the referential coordinate system. Several numerical examples pertaining to the responses of sand specimens tested under plane strain biaxial tests are finally provided. The results of numerical simulations are fairly consistent with the experimental data.