Interaction of surface waves with an array of subwavelength resonators in a granular medium

International audienceWe study experimentally the transmission, reflection and conversion of P-SV waves propagating at the surface of an unconsolidated granular half-space when scatterers are placed on their way. To design the scatterers we take advantage of the softness and consolidating property of the substrate; the scatterers consist in masses which, combined with the locally consolidating medium act as a mass-spring system on both vertical and longitudinal directions. The achieved effect is a Neumann to Dirichlet transition at high frequencies. The lowest order guided modes, whose energy is principally localized at the surface, are efficiently affected by an array of such resonators. The higher order waves, whose energy is more spread in the depth, are only slightly affected and partly mode-converted to the lowest order modes