Collapse under isotropic stress state of anisotropic and isotropic compacted soils

摘要

Deformation behaviour in collapse under isotropic stress state was studied using a controlled-suction cell. Two wetting tests are reported, which were performed on artificially prepared samples. Two different static compaction procedures were selected in order to induce the initial anisotropy: a one-dimensional procedure on volume basis and a stress-controlled isotropic compaction. Volumetric and shear strains, as well as water content changes, were measured throughout the different equalisation stages. A clear anisotropy on wetting was observed in the one-dimensionally compacted sample, which decreased progressively on suction induced plastic volumetric straining. On the other hand, the isotropically compacted sample showed an isotropic pattern of deformation on wetting. Test results are interpreted within the context of an elastoplastic framework involving a rotational component of hardening to represent the effects of the development and erasure of fabric anisotropy during plastic straining. Changes in the direction of the plastic strain increment vectors on sequential wetting are presented for the anisotropic sample.