A New Look at the Stress Dilatancy Relation in Cam-Clay Model

Abstract

A new look is offered on the energy based stress dilatancy relation in Cam-clay model (Roscoe et al., 1963). In the present study, the volume change due to dilatancy is regarded as the volume change in the void. From this view point, the hypotheses made in deriving the stress dilatancy relation in Cam-clay model will be replaced by four hypotheses as follows; (1) the void consists of contractive and dilative voids, (2) the increment of the volumetric strain in the contractive void is proportional to the increment of the plastic deviator strain of soil through the constant M, (3) the energy dissipated by the void skeleton of the dilative void is none, and (4) the tangential stiffness of soil is continuous. The four hypotheses make it possible to uncover a greater potential in Cam-clay model. In particular, it is suggested that the phase transformation line, which divides the stress space into dilative and contractive zones, should be distinguished from the critical state line.