Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/10/1996
Publication Date: N/A
Citation: Interpretive Summary: Sound waves directed at porous media are partially reflected and partially absorbed. The degree of absorption or reflection is determined by the porosity and the pore size distribution of the media. Conversely, it follows that soundwaves can be used to characterize porous media. Soil is a porous medium. This paper discusses soundwave measurements and principles on agricultural soils. It describes basic information concerning soil properties that can be obtained from this non-invasive technique, such as porosity, permeability, and pore tortuosity. This information in turn will be helpful to interpret layering effects, water content, roughness, soil strength, etc.
Technical Abstract: Acoustic phenomenon related to soils have broad applications in agricultural research. The reflection and transmission of acoustic waves from and into the pore spaces of soils depend upon air-porosity, pore tortuosity and air-permeability. The propagation of sound above rough soils is controlled by additional parameters, shape, size, and packing density of the roughness elements. Acoustic-to-seismic coupling refers to the coupling of acoustic energy from the atmosphere into the poro-elastic soil matrix. Because of the multi-phase nature of soils, wave types in addition to those of single phase materials exist. The characteristics of these waves propagating in the soil are controlled by the above parameters and the soil matrix elastic moduli and bulk density. Work at our laboratory exploiting these phenomena to study the acoustics of soils will be reviewed as well as the possibility of using these techniques to produce in-situ images of these properties on the scale of a few to one hundred centimeters