Elasto-plastic solutions for expanding cavities in strain-hardening and/or softening soils

This paper presents an analytical finite strain solution for cavity expansion in strain-hardening and/or softening Mohr-Coulomb soil subjected to a non-associated flow rule. The evolutions of material parameters, i.e. deformation and strength parameters, are totally considered. The finite strain is applied to describe the plastic behavior with the logarithmic strain. By assuming constant material properties in a very small region, the plastic region is divided into a series of concentric annuli. The solution can be recursively obtained according to the closed-form solution of each annulus, and is suitable to soil with any complex material evolution types. For the cavity with the same cavity expansion a/a0, the required cavity pressure of strain-hardening and/or softening soils is larger and/or smaller than that of elasto-perfectly plastic soils for both spherical and cylindrical cavity expansions. With respect to the same cavity pressure, the displacement and stress around cavity of strain-hardening and/or softening models are larger and/or smaller than those of perfectly plastic model. With respect to the same cavity expansion displacement, the increases in the strength parameters including cohesive strength and friction enlarge the cavity pressure, and slightly decrease the plastic and residual radii.