砂土底质浅水条件下实船地震波的检测试验

舰船低频辐射噪声在浅海的海底岩土层中引起的弹性波被称为舰船地震波，可用于识别舰船目标。为了探讨砂土底质浅海环境下舰船地震波的检测距离和信号特征，利用三分量微幅地震波检测仪，在砂土底质的内陆河道开展了实船地震波检测试验，获取了多个批次随机船只的地震波检测数据。实船地震波检测数据的时频图结果表明，在砂土底质浅水条件下，地震波信号的竖直分量传播距离相对水平分量较远，远距离地震波信号的频率成分主要为螺旋桨的轴频和倍频，多数船只基于地震波线谱的探测距离能达到1 000 m以上。

A Detecting Test of Seismic Waves Caused by Random Ships in Shallow Water with Sandy Bottom

Elastic wave in the seabed caused by low frequency noise radiated from ship is a so-called ship-induced seismic wave which can be used to identify the ship target in shallow sea. In order to investigate the detecting range and signal feature of ship-induced seismic wave in shallow sea with thick sandy bottom, a detecting test of seismic waves caused by random ships in inland river with thick sandy bottom is carried out with a three-component seismometer for weak seismic wave detection. The seismic waves caused by several random ships are obtained. According to the calculated time-frequency spectrum of the seismic waves, the propagation characteristics of seismic waves caused by ships in shallow water with thick sandy bottom are analyzed. The vertical component of seismic wave can propagate to a far distance compared with the horizontal component. The signal received by seismometer in far field is mainly caused by the noise radiated from the propeller because the line spectrum of the detected signal is almost the same as that of the propeller and always has a double frequency of the propeller's rotation frequency. The detecting ranges of most random ships are above 1 km based on the line spectrum of propeller.