Experimental measurements of the global anisotropic elastic behaviour of dry Hostun sand during triaxial tests, and effect of sample preparation

Experimental measurements have been carried out with a new, accurate, triaxial device (Triaxial StaDy) to determine the quasi-elastic properties of dry Hostun sand. The experimental investigations consist in successively applying very small axial cyclic static loadings (strain single-amplitude cycle, ε_sa ≈ 10^–5 m/m) and four types of wave, generated by piezoelectric sensors (compressive and shear waves in the axial and radial directions), at different levels of the stress–strain curve. The use of both static and dynamic results allows for an entire description of the anisotropic elastic compliance tensor at a given stress–strain state to be made. The evolutions of this tensor during triaxial loading and unloading are presented. The isotropic and deviatoric triaxial stress paths considered underline the effects of inherent and induced anisotropy respectively. The different methods used to set the sample involve clearly different kinds of anisotropic elastic behaviour, which are probably indicators of different granular structure organisations.