The Studies On Experiment Of Acoustic Attenuation Of Seafloor Sediments

Bearing all resources in the ocean in the seafloor, the study on sediments of seafloor has great meanings in the national defence and economic field. The method based on acoustics at present is a main means to survey sediments of seafloor, and attenuation is one of the key parameters of surveying the sediments of seafloor, therefore the study on attenuation becomes more and more important in ocean field. Because the difference of the temperature of every sea area of the earth causes sediments temperature not the same, and the sediments is not in on-the-spot testing mostly, the perturbation in the course of transporting, keeping and testing will cause the change in such parameters as the water content, etc., so this thesis put forward testing the connection between acoustic attenuation and temperature ,acoustic attenuation and disturbing water content to offer reference for studying and testing in acoustics or correcting.This text draw lessons from the testing system of acoustic attenuation coefficient of South China Sea Institute of Oceanlogy of Chinese Academy of Science to design the experiments to test the connections between acoustic attenuation and temperature, acoustic attenuation and disturbing water content. Having done the work of several respects around these two kinds of experiments, its concrete content and result are as follows:The experimental manual samples were made of the remnant sediments of South China Sea Institute of Oceanlogy sampling in Sep.2006 for less undisturbed samples.The frequency of ultrasonic transducers that used to the experiments is examined. The experiments are designed to computing the coefficient of conversion for energy between transducers, and drawing the curve of this coefficient and distance.The definition and formula of attenuation coefficient of temperature changing is put forward. The conclusion is made that acoustic attenuation is aggrandizing with the temperature rising.The conclusion that acoustic attenuation coefficient has different developing trends with the temperature rising is put forward by using the spectrum analysis to eliminate the disturbed data in the course of experiment. The conclusion is made that different composition of sediments, different diameter of grain, cause asymmetry of sediment during sedimentation.The connection between acoustic attenuation coefficient and water content is explored by using spectrum analysis to analyze the disturbance during experiment. The connection of disturbed attenuation changing is ruleless. On the basis of these, the recommendations are made on experimental testing.