基于改进Frequency-Bessel变换法的主动源Love波频散分析

Dispersion analysis of active Love waves based on modified Frequency-Bessel transform

近年来,Love波多道分析技术在浅地表结构探测中受到越来越广泛的应用.与Rayleigh波相比,Love波相速度不受纵波速度影响,其反演参数较少,可使反演过程更加稳定、求解的横波速度模型更加可靠.高分辨率和多模式面波频散分析是面波多道分析技术中至关重要的一环.本文利用改进Frequency-Bessel变换法对主动源Love波进行频散分析.通过改进的0阶Frequency-Bessel变换,将时间-空间域多道Love波记录变换到频率-波数域,获得其频散能量谱.通过公式推导和数值模拟,验证了该方法的有效性.实例测试表明,该方法具有较高的分辨率和多模式分辨能力,为多分量面波勘探提供了一种有效的频散分析手段.

Compared with the Multichannel Analysis of Rayleigh Waves(MASW),Multichannel Analysis of Love Waves(MALW)presents a simpler and cleaner dispersion measurement and has fewer unknown parameters in the inversion.One key step in MASW and MALW is to generate multimodal dispersion spectra.As a newly developed method,the frequency-Bessel transform method benefits from producing high-resolution multimodal dispersion spectra of surface waves from the active and passive seismic measurements.The zero and first order Frequency-Bessel transform can be used to generate dispersion spectra from the vertical and radial components of Rayleigh waves,respectively.However,to the best of the authors'knowledge,there is no relevant literature that conducts a complete study on dispersion analysis of Love waves based on the Frequency-Bessel transform.Therefore,we use the zero order modified Frequency-Bessel transform to generate dispersion spectra from active Love waves.The feasibility of this method is verified through numerical simulation and field data.In conclusion,this method has advantages in improving the accuracy of Love wave multimode dispersion measurements and thus provides a useful tool for dispersion analysis of multicomponent surface waves.