长江口与杭州湾海区水底浮泥地声模型及其声反射特性研究  

A study of geoacoustic model and acoustic reflection properties of fluid mud layer in Changjiang Estuary and Hangzhou Bay

作　　者：张叔英[1] 杨挺[2] 马在田[2] 

机构地区：[1]中科院东海研究站,上海200032 [2]同济大学海洋地质与地球物理系,上海200092

出　　处：《声学学报》1998年第5期385-393,共9页Acta Acustica

摘　　要：通过在现场和实验室分别对长江口与杭州湾海区水底浮泥重度ρ随深度变化规律以及声速C与声衰减常数β等浮泥声学参数随ρ及声波频率f的变化规律的测量和分析，得出了这个海区水底浮泥层的地声模型。其主要特点是：重度ρ（kN／m3）在10．1到15．0的范围内，随着深度线性增加，但在12．5左右处线性增加的梯度（斜率）有一个突变（拐点），ρ大于15．0以后，ρ随深度的递增加快，即浮泥层很快过渡到硬性泥层或沙层；声速c（m／s）随ρ增大的变化不明显（在±1．5％以内），但在ρ为14．0附近存在一个最小值；声衰减常数ρ（dB/m）则分别随ρ和f（kHz）线性增加。根据实测的地声模型，通过理论计算，对长江口和杭州湾海区水底浮泥层的声反射信号进行了正演模拟研究，得到了在拐点处出现的声反射特性预射波的幅度和极性）与梯度变化的关系，为解决浮泥层重度的回声探测问题提供了依据。A generalized geo-acoustic model of fluid mud layer in Changjiang Estuary and Hangzhou Bay has been derived through a large amount of in-situ measurements of the bulk density (ρ) of the layers and lab measurements of the acoustic velocity (c) and attenuation coefficient (β) of the fluid mud samples with different values of for four frequencies of 100, 150, 500, 1500 kHz. The maill features of the geoacoustic model can be expressed as follows: in the range of ρ=10.0~15.0, the bulk density of the fluid mud p increases linearly with depth z， however, there is a gradient change (knee) when ρ is about 12.5. After ρ more than 15.0, the fluid mud quickly transform into the ooze layer. In the fluid mud layer, the sound velocity c can be regarded as constant since its variation with z less than 1.5 %,and a minimum value exists when ρ is about 13.5. The variations of fi with ρ and with frequency f are linear. Based on the geo-acoustic model and the ray theory, simulations of sound reflection properties of the fluid mud layers have been made, and some significant results obtained.

关 键 词：地声模型 海底浮泥 声反射特性 海洋声学 

分 类 号：O427[理学—声学] P733.21[理学—物理]