The conventional assumptions, in most published approximations of the reflection and transmission (R/T) coefficients of plane waves at a plane interface between two anisotropic half-spaces, confine their applications to weakly anisotropic and/or weak contrast models. We consider the horizontal interface enclosed by two triclinic half-spaces to approximate the R/T coefficients normalized by the vertical energy flux. The homogeneous background medium can be anisotropic with arbitrary symmetry to better simulate the strongly anisotropic media. The second-order approximations are proposed to accommodate the strong contrast interface. We also consider an isotropic background medium under the weak anisotropy assumption. The obtained approximations can be applied to P, S1 and S2 waves, except for the transmission coefficients between the S1 and S2 waves. The S-wave transmission coefficients are insensitive to the model parameter contrasts and predominately rely on the S-wave polarization directions in the half-spaces above and below the interface. The proposed approximations are tested numerically.

中文翻译：

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三斜介质中P，S ₁和S ₂波的反射和透射系数近似

在大多数公开发表的近似于两个各向异性半空间之间的平面界面处的平面波的反射和透射（R / T）系数的常规假设中，常规假设将它们的应用限制在弱各向异性和/或弱对比度模型中。我们考虑由两个三斜线半空间包围的水平界面，以近似由垂直能量通量归一化的R / T系数。均质本底介质可以是各向异性的，具有任意对称性，可以更好地模拟强各向异性介质。提出了二阶近似值以适应强对比度界面。我们还考虑了弱各向异性假设下的各向同性背景介质。所获得的近似值可以应用于P，S 1和S除了S 1和S 2波之间的传输系数外，其余2个波。该小号-wave传输系数是不敏感的模型参数的对比和主要依靠š在半空间的上方和下方的界面-wave的偏振方向。拟议的近似值进行了数值测试。