The Study On Temperature Effecting Acoustic Properties Of Seafloor Sediments In South China Sea

According to "United Nations Convention on Law of the Sea" and China's claim, China may be under the jurisdiction of the South China Sea an area of 200×104km2. South China Sea is rich in resources especially the offshore oil and gas. The sound of sediments under the water boundary carries the marine resources, marine geology and maritime history. The research of acoustic properties and theoretical model of sound propagation has a strong application background, in the natural earthquake, geological exploration and development of oil and gas resources, disaster prevention and mitigation environmental, and so on. The research obtained certain results in South China Sea sediment's theory and experiment of characteristics of the physical and mechanical and relationship between acoustic properties, theoretical model of sound propagation, and so on. But, during the research of South China Sea sediment, many issues need to be discussed. So, we need more theoretical and experimental research to provide a strong theoretical and technical support for the South China Sea's resource development.Acoustic parameters measured of sub-bottom sediment (velocity, sound attenuation, acoustic impedance and acoustic reflection coefficient, and so on) are indispensable content of sound field of marine research and ocean exploration. And also the key seabed exploration and development of marine resources. Now there are three major ways for measuring the acoustic characteristics of sediments:one is the acoustic properties of sediments in situ measurements; one is the telemetry of acoustic parameters; another method is to measure in the laboratory after sampling. Because sediment samples can be measured repeatly, high accuracy relatively, coat low. and so on. Domestic used laboratory measurement commonly.Using attenuation measurements coaxial gap, laboratory simulation of the South China Sea bottom sediments of different temperature conditions to study marine sediment sound speed and temperature of the relationship between the South China Sea bottom sediments sound speed we draw the following rule exists:as the temperature rise high sediment sound velocity change is slow, up and down the more obvious, the overall trend is upward.This paper described three different acoustic propagation model of marine sediment, such as Biot-Stoll model, the equivalent density fluid model and FCFCM model. Under the same parameters, only considering the temperature factors, this paper analyzed numerically three models in different porosity and different frequencies of sound propagation properties respectively. This paper compared compression wave velocity of three models, analyzed the rule that theoretically compression wave velocity of sediments increases with the temperature increasing and validated rationality of three models using experimental data.This paper designed acoustic system that reflected the function of seafloor sediments acoustic system which met the need basically by using MATLAB/GUI software. The graphical user interface of the system can deal effectively with the experimental data of bottom sediment acoustic parameters (velocity, amplitude, sound attenuation) and provide us a convenient platform for data processing. Acoustic system has strengthened the MATLAB program modularity, improved interaction between users and programs and gotten satisfactory results.