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利用声学方法提取海底沉积层物理一力学性质的信息,是近年得到迅速发展的一种海底调查方法,近一、二十年间利用电子显微镜观测技术,发现沉积物一些重要的微观特征,如沉积物颗粒堆垒状态、孔隙结构和孔隙纵横比等,对声在海底沉积物中的传播特性,特别是对于沉积物的声速,具有不能忽视的影响,为了阐明海底沉积物结构-力学因素影响声传播特性的物理机制,本文研究了沉积物微观结构与其宏观声学表现之间的关系,并以南海西北部一个有代表性的陆架海区为例,对17个现场测站的一系列测试数据进行回归分析,结果表明,采用无侧限抗压强度q_u作为等效因子来综合地表达海底沉积物颗粒堆垒和孔隙结构的宏观效应,可作为利用孔隙度n计算沉积层声速c的一个补充修正项;对于本海区,可得到下面形式的经验公式: f(c,n,q_u)=c-4195+90.5833n-0.7695n~2+94.6968q_u-64.4603q_u~2=0,它提高了不考虑孔隙结构的常用公式(如Anderson公式)的计算精度,同时免除了为修正声速计算而对微观孔隙进行测量统计的必要性。
The use of acoustic methods to extract information on the physical-mechanical properties of seafloor sediments is a rapidly developing method of seafloor investigation in recent years. The use of electron microscopy in the past one or two decades has revealed some important microscopic features of sediments such as sediments Particle stacking state, pore structure and pore aspect ratio, etc., have an insignificant effect on the propagation characteristics of sound in seafloor sediments, especially for the sediment velocity. In order to clarify the structural-mechanical factors of seafloor sediment, In this paper, the relationship between the microscopic structure of sediment and its macroscopic acoustics is studied. Taking a representative shelf sea area in the northwestern South China Sea as an example, a series of regression analysis of a series of test data from 17 field stations The results show that using unconfined compressive strength q_u as an equivalent factor to synthetically express macroscopic effect of seafloor sediment particles and pore structure can be used as a supplementary correction term for calculating the sound velocity c of the sedimentary layer using porosity n. For this sea area, the following empirical formula can be obtained: f (c, n, q_u) = c-4195 + 90.5833n-0.7695n ~ 2 + 94.6968q_u-64.4603q_u ~ 2 = 0, which increases the computational accuracy of commonly used formulas that do not account for pore structure, such as the Anderson formula, while eliminating the need for measurement statistics for microscopic pores to correct for sonic velocity calculations.