Modeling acoustic nonlinearities in marine sediments

Investigations into the theoretical and numerical treatment of acoustic nonlinearities in marine sediments are motivated by mine countermeasures and other Naval interests related to explosions in shallow water. Agreement between theory and data for the nonlinearity parameter B/A has been demonstrated in early papers concerning saturated sands. In the more general case involving varying depth profiles of air and silt contents, however, it is observed that B/A values vary so greatly that deterministic nonlinear modeling approaches may have to be augmented to address environmental uncertainty. Comparisons are given between B/A values derived from static consolidation tests and available in situ data. Numerical profiles from the NPE shock propagation model are given to demonstrate the effects of environmental uncertainty. [Work supported by the ONR.]