Abstract:
Current acoustic backscatter models are limited in applicability to specific types of marine sediments. A fine-grain sediment in which particles are suspended can generally be treated as an acoustic fluid, whereas an elastic model is more appropriate over a rigid bottom. Sandy sediments have been modeled successfully as Biot poroelastic media [F. A. Boyle, and N. P. Chotiros, J. Acoust. Soc. Am. 98, 531--541 (1995)]. Since it is unclear how to treat a sediment that straddles the boundary between sediment types, a unified theory for bottom backscatter is needed, from which a seamless model can be developed. Due to the porous nature of marine sediments, a poroelastic model is considered to be most appropriate. Critical parameters that need to be determined, particularly frame moduli and permeability, are inverted from acoustic measurements, to give empirical values as a function of porosity. [Work funded by NRL Code 321 OA.]