声的产生、反射、折射和极化

Production,reflection,refraction and polarization of sound

建立P-波入射到垂直横向各向同性(vertical transverse isotropy,VTI)介质界面模型,分析异常入射角存在与不存在的两种界面模型,分别建立椭圆极化方程并利用Christoffel方程分析了岩石各向异性对非均匀折射P-波极化状态的影响。研究发现,对应折射P-波在过入射临界角的范围内存在一个异常入射角,该异常入射角会导致非均匀椭圆极化波的极化轨迹和旋转方向发生突变,且椭圆极化轨迹的形状和初始相角由入射角及介质的各向异性参数共同决定。以此为基础,构建能量转换并行传输网络模型,结果发现,实测结果与理论计算结果基本相符,该模型能够较好地描述声源换能器在电压驱动信号的激励下向外辐射的声波信号子波。

By establishing the interface model of vertical transverse isotropic(VTI),the elliptic polarization equation and the Christoffel equation are used to analyzing the two interface models with and without abnormal incident-angles,and the influence of rock anisotropy on the polarization state of non-uniform refracted P-wave.It is discovered that the corresponding P-wave refraction in the range of a critical incidence angle has an abnormal incident-angle,which leads to the non-uniform elliptical polarization of the wave trajectory and the rotation direction change abruptly.The shape of the elliptical polarization track and the initial phase are determined by the incidence angle,the incidence and the refraction of medium anisotropy parameters.The results show that the measured results are basically consistent with the theoretical calculation results,and the parallel transmission network model of energy conversion can well describe the acoustic signal wavelet radiated from the acoustic source transducer under the excitation of the voltage driven signal.