舰船海底地震波形成机理的理论分析

航行舰船是一个很大的振动和噪声源,其振动和噪声引起的压力波经由流体介质传播到海底,引起海底岩层振动,产生弹性波并向远处传播,这种航行舰船在海底引起的弹性波称为舰船海底地震波。舰船海底地震波可用于识别舰船目标,作为水中武器的目标探测信号。基于波动理论,得到了舰船引起海底地震波的波动方程和有限元数值计算模型。利用该模型,对二维半无限空间层状海洋环境在水压场和极低频点声源作用下的海底地震波信号进行了数值模拟,得到了远场海底表面处加速度和水压的时域频域信号。结果表明,在二维半无限空间层状海洋环境条件下,舰船远场海底地震波主要由舰船极低频的噪声辐射引起,主要频率范围在1-7Hz。

Theoretical Analysis to Mechanism of Seafloor Seismic Wave Induced by Sailing Vessel

A sailing vessel is a strong viberating and yawp source.The pressure wave caused by the vibration and yawp in seawater transmits into seafloor and induces elastic wave in seabed,so called seafloor seismic wave of sailing vessel.The seafloor seismic wave by sailing vessel is capable of identifing vessel target,even serves the target detecting signal of marine weapons.The wave equations and corresponding FEM of seafloor seismic wave of are developed,and a numerical simulation to seafloor seismic wave induced by the hydraulic pressure field of seaboat and low frenquent sound source point is carried out in a two dimensional hemisphere and layered sea circumstance.The acceleraion and sound pressure on the surface of seafloor are obtained.The simulation result shows that the long distance seafloor seismic wave of sailing vessel is basically produced by the low frequent yawp of sailing vessel within 1 to 7 Hz.