分层介质半空间瑞利波的时频分析
Time-frequency analysis of the dispersive Rayleigh waves in stratified media
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摘要: 对分层介质半空间瑞利波的频散特性,用一种时频分析方法——重排的平滑伪魏格纳维尔分布(RSPWVD,Reassignment of Smooth Pseudo-Wigner Ville Distribution)进行了分析和研究。对均匀半空间和两层介质半空间的理论和实验研究表明,由于层状介质中瑞利波的频散曲线存在多个模式,所获得的群速度频散曲线在不同的频段显示出来的模式是对应表面位移幅度占主导作用的模式。频散曲线的这种模式判定对利用层状半空间的瑞利波反演介质参数是必须预先了解的。Abstract: The dispersive characteristics of the Rayleigh waves propagated in a stratified media were analyzed by a time-frequency analysis method,the Reassignment of Smooth Pseudo-Wigner Ville Distribution(RSPWVD).Theoretical simulations and experiments were implemented for the homogeneous half-space and the two-layered half-space.The multi-mode effect exists in the dispersion curve of the Rayleigh wave in stratified media.The group velocity dispersion curves in different frequency ranges obtained by experimental result are all corresponding to the dominant modes in their surface displacement amplitudes.Such a mode-identification of the multi-mode Rayleigh waves is required in inversing the medium parameters.