A Simple Incremental Modelling of Granular-Media Mechanics
  It is proposed a simple non linear incremental modelling of the axi-symmetric compression of granular materials and powders. It describes the main features of undrained compression and of oedometric compression using the results of compression tests at constant lateral stress . It generalises the concept of characteristic state. It shows that trajectories arriving at a given critical state shall pertain to a single surface in the (v,q,p) space, which confirms the recent result demonstrating that Hvorslev's and Roscoe's surfaces are part of the same surface. Effects of induced anisotropy are discussed; comparison with classical camclay model is performed. 
P. Evesque