EXPERIMENTAL STUDY AND VALIDATION OF WAVE PROPAGATION MODELS FOR MARINE SEDIMENTS BY CALIBRATED REFLECTION EXPERIMENTS ON LABORATORY SCALE

摘要

Due to the extensive complexity of the seafloor as an acoustical system and the huge degree of difficulty in getting accurate and proper backscattered seafloor data, it is highly advisable to first study and validate acoustic wave propagation models through marine sediments in laboratory circumstances. A water/sediment/Plexiglass configuration is used to carry out reflection measurements on different sand types. By an inverse procedure, which is based on a maximum likelihood estimator, physical parameters of the sediment are determined. It is shown that a well chosen calibration method and an optimal choice of the initial values for the inverse procedure, lead to a fine match between the measurements and the chosen general viscoelastic model for the mechanic properties of the sediment. Although the surfaces of the prepared sands were smoothed away, it was necessarily to include surface roughness in order to obtain realistic values for the absorption in the sediment.