Abstract: It is recalled that stress-strain incremental
modelling is a common feature of most theoretical description of the mechanical
behaviour of granular material. An other commonly accepted characteristics of
the mechanical behaviour of granular material is the Rowe’s relation which
links the dilatancy K= -v/1 to the stress ratio 1/3 during a 2=3=cst test , i.e. s1/s3=(1+M)(1+K). Using the
incremental modelling, this law shall be interpreted as a pseudo-Poisson
coefficient. We combine these two features to solve the problem of an axial
compression under undrained condition. We demonstrate that the sample is submitted
to a bifurcation of the transcritical type when it reaches the q=Mp line. This
allows extending the notion of the characteristic state introduced by Luong to
other situations and to anisotropic systems. We show also that these undrained
tests are quite appropriate to study the characteristic-state behaviour.
poudres & grains 8, 1-11 (15 octobre 1999)