Sphere Penetration Experiments in Vertically Vibrated Sand

The paper concerns vibrodriving and vibrocompaction processes applied to granular soils and presents experiments able to characterize the behaviour of sand subjected to vertical vibration. Soil degradation phenomena arising during vibro-driving are first described and the vibro-fluidization of dry granular matter is discussed. The paper concentrates on the shear strength degradation of vibrated dry granular soils. Vertical vibration is then particularly investigated. The volume change during vertical vibration is described and the sand behaviour during vibration is also discussed. One focuses on the influence of the acceleration on the dry density after vibration. Finally, new sphere penetration experiments (SPE) based on the conceptual work of Barkan (1962) are performed. When sand is vertically vibrated under gravitational field, three types of behaviour are identified, depending on the acceleration amplitude: the densification behaviour, the surface instability behaviour, and the vibro-fluid behaviour. The different patterns of particles recirculation are described. The boundaries between the different regimes are defined. One proposes empirical relationships to approximate the observed volume change with time and with the number of applied cycles, within the densification regime. Concerning the SPE’s, different kinds of sinking curves are observed depending on the regime of vibration; they differ from the early results of Barkan (1962) which only presented “equivalent” Stokes sinking profiles