ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

5aPAa10. Effect of trapped gas on acoustic properties of model sediments.

Mark Wang

F. Douglas Shields

James M. Sabatier

L. Dwynn Lafleur

Natl. Ctr. for Phys. Acoust., Univ. of Mississippi, University, MS 38677

Sound speeds and attenuations have been measured in sediments contained in a steel tube 2.5 in. i.d., 3.5 in. o.d., and 5.5 ft long. Measurements have been made in two kinds of sand and three sizes of glass beads over a frequency range of 2--20 kHz. In order to study the effect of trapped gases on the acoustical properties of the sediment, a dry sediment was evacuated and then flooded with degassed water. The results are highly sensitive to the packing of the sediment, and are slightly influenced by the pumping process. The measured sound speeds and absorptions after correction for the effects of the yielding wall are compared with those expected from the Biot theory. [Work supported by ONR.]