Coupled electrokinetic-Biot theory and measurement techniques in sediment acoustics

Block, G., J.G. Harris, and N.P. Chotiros, 2003
In Proceedings of the 16th ASCE Engineering Mechanics Conference, July 16 – 18, 2003, University of Washington, Seattle, WA.


Biot theory will no doubt play an important role in modeling wave propagation in ocean sediments. One prediction of Biot theory is the existence of the Biot slow wave, described by out-of-phase motion of the pore fluid and porous grain structure. Unfortunately, slow wave motion has been extremely difficult to verify using acoustical transducers. Electrokinetic (EK) transduction techniques shed new light on this effort. EK parameters, such as the surface chemistry of the grains and pore fluid salinity, are coupled to Biot theory at the microscopic level, and therefore provide another method of determining the microstructural properties of sediments. One application of this is the electrokinetic transmission of acoustic pressure waves. This occurs when an applied voltage drives ionic (and thus fluidic) currents in electrolyte-saturated porous media. Experimental and theoretical results for electrokinetic motion in sediments will be reported. [Work supported by ONR, Ocean Acoustics.]