Influence of initial conditions and loading characteristics on stability of undrained behaviour of a loose sand

The results of a series of undrained triaxial tests are presented in this paper, carried out with a servo-controlled press on a reference sand (Hostun sand RF) in a loose state for different states of consolidation (isotropic, anisotropic) and different loading conditions in order to study the influence of these parameters on the initiation of instabilities of the " true " liquefaction type with rapid collapse and flow of the sand structure. For cyclic loadings, it is found that, similarly to the case of monotonic loadings, the existence of an initial static shear has a very unfavorable influence on stability, and the case of low amplitude cyclic loading is described, for which accommodation of the material with stabilization may be obtained under certain conditions.