High frequency acoustic properties of water-saturated sediments: laboratory study
Résumé
Acoustic properties of water-saturated sandy sediments in a frequency range going from 200 kHz to 3MHz were studied in controlled laboratory conditions. Measurements were performed at different times in order to check the repeatability of the results. Also it was studied the influence of the size distribution of the sediment by considering two different samples of medium sand with the same mean grain size, but with a different width of the size distribution. A comparison with artificial sediment made of glass beads of the same size was made to study the influence of the grain shape on the reflected and backscattered signals. The influence of the transducer directivity diagram is discussed in the case of a strong incoherent scattering. Finally, the time-frequency structure of the reflected signals was analyzed. It was found to be very sensitive to the granular structure of the sediment.