Acoustic fields in the layered gas-saturated medium

The propagation of acoustic waves and bounded beams in layered inhomogeneous medium containing gas bubbles is studied. Such system models, in particular, the acoustic processes in freshwater ponds bottom soil that contains gas-saturated sedimentary rocks. It is shown that the sound speed in gas-saturated soil is determined by amount of containing gas. If amount of gas increase to about 1% of the total volume of sediment the sound speed drops to 100 m/s, i.e. in 15 times in comparison with the sound speed in water. The reflection and transmission coefficients of acoustic waves from layered gas-saturated medium and their dependence on frequency and angle of wave incidence are calculated. A comparison with the experimental results is made. It is shown that the frequency dependence of the module of the sound reflection coefficient received at one of the areas of the Klyazminsky reservoir, has an oscillating character, and the oscillation frequency depends on the thickness of gas-saturated layer and does not depend on the incidence angle. The possibility of recovery of the structural parameters of layered soil on this frequency dependence is shown. Nonlinear acoustic effects associated with a strong structural nonlinearity of a liquid with bubbles are studied. Different cases of the sound source location relative to the bottom soil boundary are considered and evolution equations for the cases of horizontal and oblique propagation of intense waves are derived. Wave profiles and the transverse form of beams are calculated.