Love waves have great potential in geological inspection and ultrasonic nondestructive testing for near-surface underground characteristics. A thorough and effective utilization of the Love wave requires a better understanding of its scattering phenomenon. The paper studies the problem of Love wave scattering by cavity-like flaws on the interface between the upper layer and the lower half-plane. For the forward analysis, we suggest a modified boundary element method (BEM) incorporating the far-field displacement patterns, which can effectively eliminate fictitious reflections introduced by model truncation. For inverse analysis, we propose a quantitative reconstruction procedure for the flaw shape using reflection coefficients of the first-order Love wave. By theoretical deduction, it can be proved that the cavity’s geometric shape is approximately expressed as an inverse spatial Fourier transform of far-field reflection coefficients in the wavenumber domain. Numerical examples are given by substituting the reflection coefficients obtained from the forward analysis into the inversion algorithm, and high consistency is shown between the reconstructed flaw images and the geometric characteristics of the actual flaws.

中文翻译：

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界面腔对 Love 波散射的正反分析

洛夫波在近地表地下特征的地质检查和超声波无损检测方面具有巨大潜力。彻底有效地利用爱波需要更好地了解它的散射现象。论文研究了上层与下半平面界面上空洞状缺陷引起的Love波散射问题。对于正向分析，我们提出了一种结合远场位移模式的改进边界元法（BEM），它可以有效地消除模型截断引入的虚拟反射。对于逆分析，我们提出了一种使用一阶 Love 波的反射系数对缺陷形状进行定量重建的程序。通过理论推导，可以证明，空腔的几何形状近似表示为波数域中远场反射系数的空间傅里叶逆变换。通过将正向分析得到的反射系数代入反演算法给出了数值实例，重建的缺陷图像与实际缺陷的几何特征具有较高的一致性。