A homogenization approach for assessing the yield strength properties of stone column reinforced soils

The macroscopic strength properties of a purely cohesive soil reinforced by a periodic distribution of "stone columns" made of a highly frictional granular material are investigated in a rigorous way on the basis of the yield design homogenization approach. Starting from a first crude lower bound approximation to the macroscopic strength criterion of the stone column reinforced soil, a much more accurate failure surface is then drawn in the space of stresses as a result of a series of numerical elastoplastic simulations performed on the reinforced soil unit cell subject to radial strain controlled loading paths. The anisotropic characteristics of the so obtained original criterion are then highlighted by means of its representation in the Mohr plane attached to any oriented facet. The paper concludes with a first illustrative implementation of the method on the derivation of an upper bound estimate for the ultimate bearing capacity of a stone column reinforced foundation.