Effect of soil texture on the propagation and attenuation of acoustic wave at unsaturated conditions

Wei-Cheng Lo, Chao Lung Yeh, Chang Tai Tsai

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

A central issue in the successful application of acoustic wave method to detect subsurface hydrological properties is a better understanding of the influence of soil texture on the propagation and attenuation of acoustic wave as moisture content is varied, which was numerically investigated in the present study. Our earlier studies have demonstrated the existence of three different modes of acoustic wave in an elastic porous medium containing two immiscible, viscous, compressible fluids. Based on the dispersion equation obtained in the Lo-Sposito-Majer (LSM) model, the phase velocity and attenuation coefficient of the P1 and P2 waves which respectively propagate the fastest and second fastest were determined as a function of water saturation for 11 soil texture classes. The slowest wave (P3) was not characterized in this study since it does not travel far, due to very high attenuation. To provide a more general result, the calculated phase velocity and attenuation coefficient for different soil textures were normalized by those computed for sand. The normalization leads the resulting dimensionless parameters to be frequency independent throughout the whole range (up to 500 Hz) with Darcy's law remaining valid for the description of each fluid flow under wave excitation. The normalized phase velocity of the P1 wave was shown to have a substantially constant value at higher water saturations, but in the lower saturation range it first increases to reach a certain maximum value for different soil types and then decreases. The physical parameter controlling this phenomenon is the ratio of two effective non-wetting fluid storativity factors. Numerical results reveal that the normalized attenuation coefficient of the P1 wave is sensitive to soil texture and water saturation. Sand and loamy sand have the highest and second highest attenuation coefficients for the P1 wave, respectively. The magnitude of the normalized phase velocity of the P2 wave is found to be, with very few exceptions at nearly full saturations, linearly associated with the intrinsic permeability, while relating to the normalized attenuation coefficient of the P2 wave in an opposite manner. These results provide a quantitative clue for acoustic wave method to explore the physical properties in the shallow subsurface.

Original languageEnglish
Pages (from-to)273-284
Number of pages12
JournalJournal of Hydrology
Volume338
Issue number3-4
DOIs
Publication statusPublished - 2007 May 30

Fingerprint

unsaturated conditions
acoustic wave
soil texture
phase velocity
sand
saturation
porous media
travel
soil types
physical properties
permeability
water
soil water
water content
Darcy law
fluid
effect
loamy sand
methodology
fluid flow

All Science Journal Classification (ASJC) codes

  • Water Science and Technology

Cite this

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title = "Effect of soil texture on the propagation and attenuation of acoustic wave at unsaturated conditions",
abstract = "A central issue in the successful application of acoustic wave method to detect subsurface hydrological properties is a better understanding of the influence of soil texture on the propagation and attenuation of acoustic wave as moisture content is varied, which was numerically investigated in the present study. Our earlier studies have demonstrated the existence of three different modes of acoustic wave in an elastic porous medium containing two immiscible, viscous, compressible fluids. Based on the dispersion equation obtained in the Lo-Sposito-Majer (LSM) model, the phase velocity and attenuation coefficient of the P1 and P2 waves which respectively propagate the fastest and second fastest were determined as a function of water saturation for 11 soil texture classes. The slowest wave (P3) was not characterized in this study since it does not travel far, due to very high attenuation. To provide a more general result, the calculated phase velocity and attenuation coefficient for different soil textures were normalized by those computed for sand. The normalization leads the resulting dimensionless parameters to be frequency independent throughout the whole range (up to 500 Hz) with Darcy's law remaining valid for the description of each fluid flow under wave excitation. The normalized phase velocity of the P1 wave was shown to have a substantially constant value at higher water saturations, but in the lower saturation range it first increases to reach a certain maximum value for different soil types and then decreases. The physical parameter controlling this phenomenon is the ratio of two effective non-wetting fluid storativity factors. Numerical results reveal that the normalized attenuation coefficient of the P1 wave is sensitive to soil texture and water saturation. Sand and loamy sand have the highest and second highest attenuation coefficients for the P1 wave, respectively. The magnitude of the normalized phase velocity of the P2 wave is found to be, with very few exceptions at nearly full saturations, linearly associated with the intrinsic permeability, while relating to the normalized attenuation coefficient of the P2 wave in an opposite manner. These results provide a quantitative clue for acoustic wave method to explore the physical properties in the shallow subsurface.",
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Effect of soil texture on the propagation and attenuation of acoustic wave at unsaturated conditions. / Lo, Wei-Cheng; Yeh, Chao Lung; Tsai, Chang Tai.

In: Journal of Hydrology, Vol. 338, No. 3-4, 30.05.2007, p. 273-284.

Research output: Contribution to journalArticle

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