海底黏性沉积物声衰减特性研究

The relationships between attenuation and physical properties in marine sediments are of considerable importance in determining the causes of attenuation and in selecting appropriate models. In addition to the intrinsic attenuation, the attenuation, which is obtained by in-situ measurements and laboratory measurements, includes all other losses. Therefore, the correlations between the measured attenuation and physical properties are bad. This project will study on attenuation of cohesive marine sediments: With removing the effects of layering and inclusions on attenuation by remolding the sediment samples taken from Bohai Sea and Yellow Sea, the cohesive sediments which are homogeneous and saturated with physical and mechanical properties continuously changing are made; The measurements of attenuation at different frequencies and physical and mechanical properties of the sediments are conducted, and the microstructure are observed by sampling simultaneously. The relations which are more reliable will be put forward by analyzing the attenuation change of cohesive sediments with frequencies, bulk density, water content, porosity, shear strength, clay content, mean grain size, etc. And the attenuation mechanism of cohesive marine sediments will be discovered by studying the microstructure of the sediments. The aim of this project is to promote the acoustic modeling of cohesive marine sediments and to support the acoustic detection technology. The work has great significance in theory and application.

海底沉积物声衰减特性与物理性质之间的关系对于确定声衰减原因及选择合适的理论计算模型非常重要。原位测量和取样实验室测量获得的声衰减既包括固有衰减，也包括声波在沉积界面和其他沉积物非均匀体处的转换以及声波的散射等，导致其与物理性质之间的相关性普遍较差。本项目聚焦研究相对较少的海底黏性沉积物的声衰减特性，利用在渤、黄海取得的黏性沉积物样品，通过重塑去除沉积分层及包含物等对声衰减的影响，得到物理力学性质连续变化的均匀饱和沉积物，开展不同频率下的声衰减测量，同步测试物理力学性质、取样观测微结构；分析声衰减随频率、沉积物密度、含水量、孔隙度、抗剪强度、黏粒含量、平均粒径等的变化，建立可信度大幅提高的声衰减与频率及物理力学性质之间的关系式；结合微结构图像处理分析，揭示海底黏性沉积物的声衰减机制，促进海底黏性沉积物的声学建模，为声学探测技术提供支撑，具有重要的理论和实际意义。

海底沉积物声衰减特性与物理性质之间的关系对于确定声衰减原因及选择合适的理论计算模型非常重要。原位测量和取样实验室测量获得的声衰减往往既包括固有衰减，又包括声波在沉积界面和其他沉积物非均匀体处的转换以及声波的散射等，导致其与物理性质之间的相关性普遍较差。本项目聚焦研究相对较少的海底黏性沉积物的声衰减特性，利用均匀饱和的海底黏性沉积物样品，开展了不同频率下的声衰减测量，并测试了沉积物样品的物理力学性质，取样观测了沉积物样品的微结构，分析了声衰减与频率、沉积物密度、含水量、孔隙度、抗剪强度、黏粒含量、平均粒径、微结构参数的关系，给出了声衰减与沉积物密度、含水量及孔隙度的回归公式，探讨了海底黏性沉积物的声衰减机制。另外，本项目还对海底沉积物声速/声衰减特性的实验室测试技术进行了系统深入地分析，研制出了三种沉积物声速/声衰减测试装置。本项目的研究成果可促进海底黏性沉积物的声学建模，为声学探测技术提供支撑，具有重要的理论和实际意义。