Investigation of long-term creep deformations on soil strength

摘要

Clays under high shear stress levels can exhibit significant loss of long-term shear strength which can even cause delayed creep-induced failure. While volumetric creep (often called secondary compression) tends to increase the shear strength, deviatonc creep has deleterious effects on shear strength which often prevail in the overall soil behaviour. The paper presents an incremental elastoplastic-viscoplastic constitutive model based on the overstress theory for natural clays possessing structure. The model combines structure/strength degradation due to plastic shear strains and strength envelope degradation due to creep shear strains The elastoplastic-viscoplastic constitutive model incorporates a Structure Strength Envelope along with an Intrinsic Compressibility Framework, to account for structural degradation associated with plastic strain evolution. On the other hand, strength envelope degradation is realized through the evolution of the inclination of the critical state line in strength space to a residual state Model predictions tested in triaxial shearing mode reveals thai the model can predict tertiary creep behaviour, i e., long-term creep-induced failure under high shear stress levels The model is implemented in the commercial F.E. Code ABAQUS and used in the bearing capacity of surface foundations.