Field experiments on the velocity dispersion and attenuation of acoustic waves through sandy sediments in shallow waters

Abstract

The velocity dispersion and attenuation of acoustic waves though a sandy bottom in a shallow ocean were measured for a broad frequency band of 1–500 kHz using a buried horizontal hydrophone array and several broadband piezoelectric sources. The sands have a fairly uniform grain size of 0.22 mm and a porosity of 0.44. The experimental data were compared with the Biot theory, the BISQ theory, the squirt flow theory and the patchy-saturated theory. The data–theory comparisons indicate that the Biot theory best predicts the acoustic propagation though the sand bottom in shallow water in the medium to high frequency band of 1–500 kHz. The data–theory comparisons also confirm that the permeability, porosity, and added mass coefficient of shallow water sediments can be extracted from acoustic data. [Work supported by ONR Code 321 OA.]