Cavity expansion in strain hardening frictional soils under drained condition

A rigorous semianalytical solution for the drained expansion of a cylindrical cavity in frictional soils is presented. Following the restrict material (Lagrangian) description approach recently developed by the authors, the cavity analysis has been extended to the 3-invariant plasticity soil model, which is governed by the Matsuoka-Nakai yield criterion combined with the friction angle hardening depending on the development of deviatoric plastic strain. The 4 desired first-order ordinary differential equations are subsequently derived, which enable the 3 stress components, volumetric strain, and plastic shear strain in the plastic zone to be readily calculated through the standard numerical procedure. Numerical examples illustrate how the major constitutive parameter, in situ stress state, and the third stress invariant impact the overall response of the cavity as well as its ultimate pressure. Specific consideration is given to the influence of the plastic hardening parameter on the stress path of a soil element at the cavity wall.