南海南部海底沉积物声学性质及物理参数相关关系研究

发布时间：2018-05-06 14:15

本文选题：海底浅表层沉积物 + 声学性质和物理参数　；参考：《中国科学院研究生院(海洋研究所)》2016年博士论文

【摘要】：海底浅表层沉积物作为海水与海底的分界面,是海洋声场环境的一个重要组成部分,是海洋资源调查不可缺少的研究内容,海底沉积物声学特性与物理力学等参数的关系在海洋工程建设、海底资源勘察、海洋军事发展与安全等领域具有重要的应用价值。论文主要对南海南部浅表层海底沉积物的声学性质和物理参数之间的相关关系进行了系统性的研究。研究区域位于南海南部,在南海南部21个站位采集了浅表层海底沉积物柱状样品,其中,2个站位的柱状样品来自于陆架地区,13个站位的柱状样品来自于陆坡地区,6个站位的柱状样品来自于南沙海槽。当海底沉积物样品被采集上来后,在甲板上利用改进的同轴差距测量法对柱状样品进行了声速测量,随后在实验室中对沉积物样品的物理参数进行了相关测量,包括孔隙度,密度,中值粒径,含水量等物理参数。根据实际测量的数据,对声速和物理参数之间的线性关系进行研究,采用数学方法对测量数据进行了统计和回归分析,建立了声速-物理参数的单参数方程。将南海南部的实测数据带入前人建立的声速预测方程与本文建立的单参数方程中进行比较,发现根据前人经验方程预测出的声速值与实际测量的声速值存在差异,结果表明前人建立的方程并不适用于南海南部,声速预测方程具有地域局限性。本文对于产生这种差异的可能性原因进行了探讨和研究,结果表明预测方程的地域差异性与沉积物类型,地理特征(沉积环境),沉积物物理性质以及沉砂泥比等有关。对南海南部不同沉积环境下采集的沉积物柱状样品进行了分析测量,在此基础上建立了沉积物声速与物理参数的双参数经验方程。在双参数方程的基础上,利用误差范数分析法对影响海底沉积物声速的物理参数进行了敏感性分析,分析结果表明孔隙度是影响沉积物声速的主要因素,并且总结出了沉积物声速对于各个物理参数的敏感性大小:孔隙度湿密度粘土含量中值粒径。本文对沉积物声速和物理参数之间的反演理论进行了相关研究,在前人研究的基础上,对Gassmann方程进行公式变换,利用孔隙度和纵波声速的相关关系求解出孔隙度预测公式,并将该公式应用于南海南部海底沉积物孔隙度预测中。将Gassmann方程预测结果与沉积物柱状样品实验室测量结果进行对比研究,结果表明Gassmann方程能够较好的预测海底沉积物的孔隙度,对浅海地区的孔隙度预测尤为准确。利用误差范数分析法对Gassmann方程各输入参数进行敏感性分析,发现沉积物纵波声速对孔隙度预测精度影响最大。
[Abstract]:As the interface between sea water and seabed, shallow surface sediment is an important part of the environment of ocean sound field, and is an indispensable research content of marine resource investigation. The relationship between acoustic characteristics and physical and mechanical parameters of seabed sediments has important application value in the field of ocean engineering, seabed resources exploration, marine military development and safety. The correlation between acoustic properties and physical parameters of shallow surface sediments in the south of the South China Sea is systematically studied in this paper. The study area is located in the southern part of the South China Sea, and the columnar samples of shallow surface seafloor sediments were collected at 21 stations in the south of the South China Sea. Among them, the columnar samples of 2 stations came from the continental shelf area, 13 from the continental slope area, and 6 from the Nansha trough. When seabed sediment samples were collected, sound velocities of columnar samples were measured using an improved coaxial differential measurement method on deck, and then the physical parameters of sediment samples were measured in the laboratory, including porosity. Density, median particle size, water content and other physical parameters. According to the measured data, the linear relationship between the velocity of sound and the physical parameters is studied. The statistical and regression analysis of the measured data is carried out by mathematical method, and the single-parameter equation of the sonic velocity-physical parameter is established. By comparing the measured data from the south of the South China Sea with the prediction equation of sound velocity established by predecessors and the single parameter equation established in this paper, it is found that there is a difference between the predicted value of sound velocity based on the previous empirical equation and the measured value of sound velocity. The results show that the established equations are not suitable for the south of the South China Sea, and the prediction equation of sound velocity has regional limitations. In this paper, the possible causes of this difference are discussed and studied. The results show that the regional difference of the prediction equation is related to the type of sediment, the geographical characteristics (sedimentary environment, physical properties of sediment and the ratio of sediment to sediment). Based on the analysis and measurement of sediment columnar samples collected in different sedimentary environments in the south of the South China Sea, a two-parameter empirical equation of sound velocity and physical parameters of sediment was established. Based on the two-parameter equation, the sensitivity of the physical parameters affecting the sound velocity of sediment is analyzed by means of error norm analysis. The results show that porosity is the main factor affecting the sound velocity of sediment. The sensitivity of sediment acoustic velocity to various physical parameters is summarized: porosity wet density clay content median particle size. In this paper, the inversion theory between the acoustic velocity of sediment and the physical parameters is studied. On the basis of previous studies, the Gassmann equation is transformed into a formula, and the porosity prediction formula is solved by using the correlation relation between porosity and longitudinal sound velocity. The formula is applied to the prediction of the porosity of seabed sediments in the south of the South China Sea. The results of Gassmann equation are compared with the results of laboratory measurements of sediment columnar samples. The results show that the Gassmann equation can well predict the porosity of seafloor sediments, especially in shallow sea areas. The sensitivity of input parameters of Gassmann equation was analyzed by means of error norm analysis. It was found that the velocity of longitudinal wave of sediment had the greatest influence on the accuracy of porosity prediction.
【学位授予单位】：中国科学院研究生院(海洋研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P733.2;P714

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