STRESS RATE-ELASTIC STRETCHING RELATIONS IN ELASTOPLASTIC CONSTITUTIVE EQUATIONS FOR SOILS

 KOICHI HASHIGUCHl and IAN. F. COLLINS

ABSTRACT Research on the elastoplastic constitutive equations of soils has a long history. An elastic constitutive equation in a rate form is a key component of the full elastoplastic constitutive equation. However, a fully satisfactory elastic constitutive equation has yet to be found; it remains an unsolved problem although it would seem to be quite simple. In this article a physically acceptable, yet simple elastic constitutive equation for soils in rate form is proposed and incorporated in the subloading surface model. The elastic bulk and the shear moduli are made to depend on the hardening function, defining the current yield surface, which plays the role of an internal plastic variable. The pertinence is verified by comparison with test data on sand.

Key words: constitutive equation of soil, elasticity, plasticity, stress, (subloading surface model) (IGC: D6/E2)