基于声压敏感核的水下声场地声参数敏感性分析

Sensitivity analysis of geoacoustic parameters in underwater acoustic field based on pressure sensitivity kernel

使用有限频敏感核研究了水下声场对地声参数的敏感特性。利用一阶Born近似推导了接收信号复声压对海底声速变化的敏感核,采用波数积分方法仿真计算声场,得到了不同频段下海底敏感核的幅值及空间分布,分析了不同频段水下声场对海底地声参数的敏感特性。在近距离上结合南黄海海域多道地震实验数据,对利用声压敏感核的幅度进行海底参数敏感特性分析的可行性进行了验证。将该分析方法推广至典型地声环境下,仿真结果表明,近距离传播条件下甚低频段声传播需考虑深达岩石层的地声参数的影响;中高频段则仅需计入多种固结程度沉积层的影响,沉积层下可视为半无限均匀基底。而对于远距离传播,所需考虑的海底层数及深度可根据敏感核的分布相应减小。此外,通过仿真分层海底底质参数对传播损失及时频特性的影响验证了上述结论。

This paper investigates the sensitivity properties of the underwater acoustic field to geoacoustic parameters using the finite-frequency sensitive kernel.The sensitivity kernel of the complex pressure to the seabed sound speed variation is derived using the first-order Born approximation.The wavenumber integration method is used to simulate the sound field and obtain the amplitude and spatial distribution of the seabed sensitivity kernel at different frequency bands.The sensitivity characteristics of underwater sound field to seabed geophysical parameters are analyzed.By processing multi-channel seismic experimental data in the South Yellow Sea,the feasibility of analyzing geoacoustic parameters sensitivity characteristics using the amplitude of the pressuresensitivity kernel is verified.The analysis method is extended to typical geoacoustic environments,and the simulation results show that in the near-field propagation conditions,the influence of geoacoustic parameters reaching deep into rock layers needs to be considered in the very low-frequency band,while in the mid-to-high-frequency bands,only the effects of various consolidation sediment layers need to be considered.For long-distance propagation,the number of seabed layers and depth to be considered can be correspondingly reduced based on the distribution of sensitivity kernels.Furthermore,the effect of simulated layered geoacoustic parameters on transmission loss and time-frequency characteristics confirms the above conclusions.