Micro‐Macro Transition and Linear Wave Propagation in Three‐Component Compacted Granular Materials

Recently, Albers developed a continuum model for the description of wave propagation in partially saturated, three‐component, porous media. Macroscopic parameters have been obtained by a systematic micro‐macro transition procedure. Using this model, acoustic properties of sandstone filled by different pore fillings and of several soil types containing a water‐air‐mixture have been presented. The soil types are classified in the German standard DIN 4220. Originally, both for rocks and soils the shear modulus had been proposed according to the classical elasticity theory. However, it seems that this approach for granular soils yields, at least for the shear wave, wave speeds which are higher than experimentally observed values. Therefore, in this note, phase speeds and attenuations of the four waves appearing in unsaturated compact granular media are calculated using also another approach for the shear modulus, the Mindlin‐Duffy approach. The numerical results of both theoretical approaches are compared to experimentally obtained values. It turns out that the latter approach for granular media is much better while for porous media the first approach is concordant with measurements.