Formulation and application of a general inelastic locus for geomaterials with variable porosity

Numerous expressions have been developed to represent the locus of yielding, plastic potential, and failure conditions of geomaterials. In this paper, the authors first recall the characteristics of some relatively common tridimensional criteria used to describe the elastic limit and failure strength of porous materials. It is then shown that the main features of a large number of existing expressions can be represented by a set of unified equations. The ensuing locus in the multiaxial stress space is applicable to a wide range of geomaterials and loadings. A particularity of the proposed formulation is that it is explicitly porosity dependent. The validity of the general formulation is demonstrated by experimental results obtained for various types of materials. A sample application is then shown for the elastoplastic analysis of the stress distribution around a cylindrical opening.