Plane Strain Constitutive Equations for Soils

Abstract

An attempt is made to clarify certain aspects of the modeling of behavior of particulate materials. The issues are presented in terms of an incremental Hooke's law. The formulation accounts at least partially for the effects of inherent and stress‐induced anisotropy and for the effects of direction and rotation of the stress increment vector. Arguments are presented to indicate that plane strain in particulate materials is approximately two‐dimensional, with in‐plane normal stresses and longitudinal strains uncoupled from out‐ofplane stress. Particulate materials exhibit stress‐path‐induced anisotropy as well as stress‐magnitude‐induced anisotropy. A given particulate material may be cross‐anisotropic in triaxial compression but two‐dimensional in plane strain. Hooke's law is used as a vehicle for presentation of the issues because of its familiarity to geotechnical engineers and its continued use in practice.