Published online by Cambridge University Press: 01 January 1992
By considering a drained cohesionless granular sample made up of rigid grains and submitted to a triaxial test, we derive an equation relating the dilatancy K, the deviatoric stress q and the confining pressure p to the energy losses D plasticdue to plastic yielding. We demonstrate that the system is contracting (K ≤ 0) at q=0, when q is increasing and that spontaneous uncontrolled yielding begins occurring when dilatancy K is maximum. We also demonstrate the existence of the characteristic state introduced by Luong and Habib and the existence of the critical state of Schofield and Wroth. We give at last a method to determine the plastic losses during a triaxial cell test using the experimental data.