三轴非均匀弹性体强散射的多重散射理论：理论基础和应用
Multiple scattering theory for strong scattering heterogeneous elastic continua with triaxial inhomogeneities: theoretical fundamentals and applications
摘要：
介观不均匀体的几何形状在决定弹性波在非均匀介质中的宏观传播行为方面起着重要的作用。非等轴不均匀性可导致各向异性的波速和衰减。发展一种精确的散射理论来描述微结构特征与波传播参数之间的定量关系，对于地震学和超声无损检测具有重要意义。本文提出了一种适用于具有一般三轴非均匀性的强散射弹性介质的多次散射理论。通过引入适当的非正交椭球坐标，导出了均匀参考介质中各向异性格林张量形状相关奇异性的封闭解析表达式。利用费曼图技术和一阶光滑近似，导出了相干波场的重整化Dyson方程。数值计算了非均匀岩石圈几种典型介质模型中相干波的精确频散曲线和逆Q因子。对纵横比为1 ~ 7的小尺度不均匀性的数值计算结果与实际地震的结果吻合较好。速度频散的结果对不同震相的形成机制提出了新的解释。新模型在地震学和超声微结构表征中具有潜在的应用价值。
英文摘要：
The geometry of mesoscopic inhomogeneities plays an important role in determining the macroscopic propagation behaviors of elastic waves in a heterogeneous medium. Nonequiaxed inhomogeneities can lead to anisotropic wave velocity and attenuation. Developing an accurate scattering theory to describe the quantitative relation between the microstructure features and wave propagation parameters is of fundamental importance for seismology and ultrasonic nondestructive characterization. This work presents a multiple scattering theory for strongly scattering elastic media with general triaxial heterogeneities. A closed analytical expression of the shape dependent singularity of the anisotropic Green tensor for the homogeneous reference medium is derived by introducing a proper nonorthogonal ellipsoidal coordinate. Renormalized Dyson equation for the coherent wave field is then derived with the help of Feynman diagram technique and the first order smoothing approximation. The exact dispersion curves and the inverse Q-factors of coherent waves in several representative medium models for the heterogeneous lithosphere are calculated numerically. Numerical results for smallscale heterogeneities with the aspect ratio varying from 1 to 7 show satisfactory agreement with those obtained from real earthquakes. The results for velocity dispersion give rise to a novel explanation to the formation mechanism of different seismic phases. The new model has potential applications in seismology and ultrasonic microstructure characterization.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
