Research on Acoustic Properties of Seafloor Sediment with Temperature and Pressure Controlled

Abstract

The submarine in-situ environmental state was simulated to study the acoustic properties of seafloor sediments of the South China Sea in different temperature and pressure environments in this article with the application of the small-scale acoustic measurement system of seafloor sediments. Some conclusions could be drawn, including: (1) the velocity and center frequency of sound wave propagation of sediment are influenced by temperature more than by water pressure in different depth; (2) with the temperature rising, the sound velocity and the energy dissipation increase while the center frequency of sound wave propagation decreases; and (3) with the seawater pressure rising, the sound velocity varied little within 1% through a depth of 1500 m and the energy dissipation decreases large. So when correcting the laboratory measurement sound speed into the in-situ data, it should be noticed that the influence of temperature differing from the in-situ environment is significant and the influence of water pressure variation may be omitted. The variation of the acoustic attributes of the experimental sample showed greatly nonlinearity when the temperature changes, which might result from a lot of coarse sand and shell remains scattered in the measured sediment sample. Compared to the linear acoustic properties of reconstructed samples with an even structure it is maybe the reason for nonlinear variation of acoustic properties due to the uneven structure. Moreover, the correction method of Hamilton with the sound-speed ratio of sediment to bottom seawater should be used with caution due to the nonlinear variation character.