Analysis of cylindrical cavity expansion in anisotropic overconsolidated clays using the Extended UH model

Abstract

Anisotropy and overconsolidation are two important features of depositional clay and are not comprehensively addressed in current cavity expansion solutions. Aiming at better modeling the cavity expansion responses in the natural soils, this paper develops a novel and rigorous elastoplastic semi-analytical solution by implementing the advanced anisotropic unified hardening (UH) model in conjunction with incorporating the anisotropic SMP criterion. The novel incorporation of the anisotropic SMP criterion and the proper consideration of overconsolidated properties are the major contributions of the present solution. By utilizing the anisotropic stress transformation method, the initial stress-induced anisotropy, anisotropic yielding and anisotropic failure of soil are also incorporated into the proposed solution. Following the derived constitutive equations in incremental form and large strain theory, both undrained and the drained cases are reduced to boundary-value problems consisting of several first-order ordinary differential equations formed in the Lagrangian scheme. Detailed parametric analyses are presented and compared with other existing solutions to investigate the effects of anisotropy and initial overconsolidation on the cavity responses. The present solution could properly capture the cross-anisotropy and 3D strength of overconsolidated soil and hence provides a more advanced and generic approach for modeling the cavity expansion responses in wide ranges of soils.