Comments on 'On pore fluid viscosity and the wave propertiesof saturated granular materials including marine sediments'[J. Acoust. Soc. Am. 122, 1486-1501 (2007)] (L)

摘要

The ability of the grain shearing (GS) and viscous grain shearing (VGS) models to relategeophysical and acoustic properties is tested by a method based on the claimed tight couplingbetween compressional and shear wave speeds and attenuations, which allows the test result to bequantified in a single parameter. The VGS model is claimed to provide a better fit to the measuredsound speed and attenuation in sandy sediments below 10 kHz. In situ measurements of wavespeeds and attenuations from the Sediment Acoustics Experiment 1999 (SAX99) and publishedlaboratory measurements by Prasad and Meissner [Geophysics 57, 710-719 (1992)] on a number ofsand samples were used to test the models. By this metric, the SAX99 data show that the VGSmodel is no better than the original GS model because the improved agreement of compressionalwave speeds at low frequencies is achieved at the expense of gross overestimation of the shear waveattenuation. When applied to the measurements by Prasad and Meissner, it is shown that the GSmodels are not applicable at any significant confining pressures, and at zero pressure they may onlybe applicable to a small subset of the sand samples.