声波在水-含气沉积物界面的反射

含气泡海洋沉积物的声学特性是海底探测的重要问题。为了研究气泡存在对水-含气沉积物界面声反射系数的影响,本文基于气泡振动修正的Biot波动方程推导了气泡存在修正的Biot弹性模量,并结合水-沉积物界面的“开孔”边界条件推导了声波从水入射到水-含气沉积物界面的反射系数。数值分析表明气泡的振动导致反射系数呈现显著的频率特性。在气泡共振频率附近,由于气泡的共振引发的强散射和强衰减,使得反射系数很大,无论以何种角度入射,声波都很难进入含气泡的沉积物。本文研究结果表明,气泡半径、含量、声波频率以及入射角度都是影响水-含气沉积物界面反射系数的主要因素。 

Reflection of acoustic waves at a water-gassy sediment interface

Acoustic property of gassy sediment is an important problem for seafloor prospecting. In order to study the effect of gas bubbles on the reflection coefficient at a water-gassy sediment interface, the corrected Biot elastic moduli involving gas bubble pulsations are derived based on the Biot wave equation corrected by linear bubble oscillations. Then the reflection coefficient is derived through combining the "open pore" boundary condition. Numerical analysis shows the reflection coefficient presents significant variation versus frequency due to bubble oscillations. For wave frequency near the bubble resonance frequency, bubble resonances cause high scattering and high attenuation, which induces to a high reflection coefficient and a poor acoustic penetration at water-gassy sediment interface. And numerical analysis indicates the volume concentration, the bubble size, the wave frequency and the angle of incidence are important parameters affecting the reflection coefficient at a water-gassy sediment interface.