浅海低频点声源作用下海底地震波的数值模拟

Numerical Simulation of Seafloor Seismic Wave Caused by Low Frequency Point Sound Source in Shallow Water

建立了点声源作用下海底地震波的时域数值计算模型.利用该模型,对二维半无限空间简单海洋模型的低频点声源海底地震波问题进行了数值模拟,得到了海底表面处的加速度和声压值.结果表明,浅海低频点声源的大部分能量耦合到海底基岩中以地震波的形式向远处传播.声源频率、海底吸声系数和海底基岩阻尼系数对舰船海底地震波信号均有影响.

The elastic wave in the seabed caused by sailing vessel is the so called ship seismic wave which can be used to identify ship target. According to wave theory, the wave equation and FEM algorithm of seafloor seismic wave caused by low frequency point sound source in shallow water are developed in this paper. Based on the algorithm method, a numerical simulation of seafloor seismic wave induced by low frequency point sound source is carried out under a two dimensional hemisphere and layered sea circumstance. The acceleration and sound pressure on the surface of seafloor are obtained. The simulation result shows that the energy of low frequency source in shallow water coupled mostly into the seabed and transmitted in the form of seismic wave. The amplitude of ship seismic wave varies with the frequency of point source, absorption coefficient of seafloor and damp coefficient of seabed terrane.