Elastoplastic Solution to Drained Expansion of a Cylindrical Cavity in Anisotropic Critical-State Soils

This paper presents an elastoplastic solution for drained expansion of a cylindrical cavity in anisotropic critical-state soils. The large deformation theory and the advanced anisotropic critical-state soil model S-CLAY1, which is capable of reflecting the initial anisotropy and the development of anisotropy produced by the plastic volumetric and deviatoric strains, are employed to model the elastoplastic behavior of the soil during expansion. The problem considered is formulated as a system of seven first-order ordinary differential equations in terms of the Lagrangian description with three stress components, three anisotropic variables, and the specific volume as the basic unknown variables, and the system is then solved as an initial value problem. The results, including the distributions of the seven basic variables around the cavity, effective stress paths, anisotropic parameter paths, and evolution of the yield curve are presented and compared with those from FLAC3D numerical model and some other solutions to verify the current solution and emphasize the significant effects of plastic deviatoric strain-induced anisotropy on the cavity expansion responses. The results demonstrate that the present solution is more advanced than the other solutions, and the plastic deviatoric strain-induced anisotropy has pronounced effects on the expansion response, especially in overconsolidated soil. It is expected that more reasonable predictions could be made by the proposed solution when it is applied to practical geotechnical problems.