Simpson Harry J, Houston Brian H, Liskey Steve W, Frank Philip A, Berdoz Alain R, Kraus Larry A, Frederickson Carl K, Stanic Steve
Physical Acoustics Branch Code 7136, Naval Research Laboratory, Washington, DC 20375, USA.
J Acoust Soc Am. 2003 Sep;114(3):1281-90. doi: 10.1121/1.1594192.
Acoustic bottom penetration experiments were carried out in a medium-grain sandy bottom at a site in St. Andrews Bay, Florida. These investigations used a new buried, vertical, one-dimensional synthetic array system where a small hydrophone was water-jetted into the sediment to a depth of approximately 2 m. Once buried, this hydrophone was mounted to a vertical robotics stage that translated the hydrophone upward in 1-cm increments. A broadband (3 to 80 kHz) spherical source, positioned 50 cm above the sediment-water interface, was used to insonify the sediment. Measurements were made with insonification angles above and below the critical angle by changing the horizontal distance of the source relative to the insertion point. This new measurement system is detailed, and results are presented that include temporal, frequency, and wavenumber analysis for natural and roughened interfaces. The measured compressional sound speed and attenuation are shown to be self-consistent using the Kramers-Kronig relation. Furthermore, only a single fast compressional wave was observed. There was no observation of a second slower compressional wave as predicted by some applications of the Biot model to unconsolidated water-saturated porous media.
在佛罗里达州圣安德鲁斯湾的一个中粒砂质海底进行了声学海底穿透实验。这些研究使用了一种新的埋入式垂直一维合成阵列系统，其中一个小型水听器通过水喷射被埋入沉积物中，深度约为2米。一旦被埋入，这个水听器被安装到一个垂直的机器人平台上，该平台以1厘米的增量将水听器向上移动。一个位于沉积物 - 水界面上方50厘米处的宽带（3至80千赫）球形声源被用来对沉积物进行声照射。通过改变声源相对于插入点的水平距离，在临界角上下的声照射角度下进行测量。详细介绍了这个新的测量系统，并给出了包括自然和粗糙界面的时间、频率和波数分析的结果。利用克拉默斯 - 克朗尼格关系表明，测得的纵波声速和衰减是自洽的。此外，只观察到了一个快速纵波。没有观察到如比奥模型在一些未固结水饱和多孔介质应用中所预测的第二个较慢的纵波。
