Trajectories of loose sand samples in the Phase Space of Soil Mechanics :


P. Evesque: Lab MSSM, UMR 8579 CNRS, Ecole Centrale Paris, 92295 Châtenay-Malabry, France,


Abstract: In general, the evolution of soil submitted to simple stress-strain paths is characterised using the 3d phase space (v,p',q) i.e. (specific volume, mean intergranular pressure, deviatoric stress q=s'1-s'2. When compressions is performed at s'2=s'3=cst or at p'= (s'1+s'2+s'3)/3=cst,  one finds that all trajectories end up at a line of attracting point called the critical-state line via the surface of Roscoe or of Hvorslev depending if the initial volume is the loosest possible one (at a given p') or denser. Trajectories of weakly dense samples is not often reported in this phase space. We find here that it shall present some sigmoid shape as it can be found from soil mechanics argument. This seems to indicate that Roscoe's surface shall exhibit a singularity at the critical point.


poudres & grains 11 (4), 60-63 (décembre 2000)