MODEL RESEARCH OF SEA BOTTOM SEDIMENTS

摘要

The implementation of the acoustic waves for the seabed research requires a precise diagnosis of the topic from both the theoretical and practical side. One of the most efficient tool for determination of the seabed structure is a parametric sonar based on nonlinear interaction of finite amplitude waves. It allows to investigate the seabed's structure up to tens meters below the water - sediments boundary. Little differences between the parameters of sediments as well as irregular distance between layers create difficulties in interpretation of the images of cross sections of the sea bottom. Since the description of the seabed is made on the basis of reflected impulse shape, which provides the information about the structure and material properties such as density and speed of wave propagation, the important role among other things has the spatial resolution, because the pulse length determines the possibility of distinguishing between the layers. Knowledge of acoustical properties of sediments is the matter of high importance in modelling the phenomenon of acoustic wave penetration into the sea bed. The paper will present the results of model research that were done by using the numerical model of stratified structure of the seabed in the form of a liquid on which falls the perpendicular elastic wave complemented by laboratory measurements of model of layers composed of real sea bottom sediments. The primary objective of the paper is to present the results of theoretical analysis related to the sequence of pulse propagation in real conditions with the possibility of a comparison with samples of the seabed collected from the area of sounding.