Characterization of natural sand under complex dynamic loading

An experimental study, conducted with an advanced triaxial press, evaluates the effect of different loading paths on the dynamic behavior of natural Swiss sand. Emphasis is put on comparison between the dynamic parameters evaluated in a single loading (with cyclic deviatoric part only), and the parameters obtained in complex loadings (a cyclic compressive stress is added) combined with medium to high strain levels. The superposition of a deviatoric cyclic stress and a purely compressive cyclic stress influences excess pore water pressure and strain amplitude. It thus affects the dynamic parameters. The phase angle is the key parameter for the nonlinear effect.