Acoustic probing of the contact network dynamics in a granular medium during shear-band formation

International audienceWe investigate the quasistatic mechanical response of a glass bead pack during the shear band formation using a direct shear apparatus. Combined measurements of acoustic velocity and amplitude have been conducted to probe the microstructure evolution from the quasi-elastic regime to the steady-state flow. A clear signature of a shear band formation appears in acoustic transmission. Moreover, a correlation technique of multiply scattered waves is applied to examine the transition of granular media towards failure. The pulse-like loss of correlation is observed when approaching the yield stress, revealing an intermittent dynamics of the force network