粘弹介质勒夫波频散曲线研究及应用  

A study of dispersion curves of Love waves in viscoelastic media and their application

作　　者：张保卫[1,2] 董晋 吴华 ZHANG Bao-Wei;DONG Jin;WU Hua(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China;National Center for Geological Exploration Technology,Langfang 065000,China;The Third Railway Survey and Design Institute Group Corporation,Tianjin 300251,China;School of Science,Chang'an University,Xi'an 710064,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,河北廊坊065000 [2]国家现代地质勘查工程技术研究中心,河北廊坊065000 [3]铁道第三勘察设计院集团有限公司,天津300251 [4]长安大学理学院,陕西西安710064

出　　处：《物探与化探》2020年第3期599-606,共8页Geophysical and Geochemical Exploration

基　　金：国家重点研发计划项目(2018YFF01013504);中国地质调查局地质调查项目(DD20189133,DD20190556);国家自然科学基金项目(41874123,41004043);长安大学中央高校基金项目(300102268402,300102129111);物化探所中央财政科研项目结余资金资助项目(JY201703)。

摘　　要：研究表明,与瑞利波方法相比,勒夫波具有频散曲线求解更加简单、数据信噪比更高、频散曲线反演对初始模型的依赖程度更低等优点,已开始在众多领域得到应用和推广。但还存在一些亟待解决的问题,比如在实际的地球模型中,地层介质是具有粘弹性的,尤其是近地表第四系软土对地震波的吸收衰减作用更为显著。因此,开展粘弹介质勒夫波理论频散曲线研究具有重要的现实意义。本文通过求解频散方程获得勒夫波理论相速度频散曲线,采用高阶有限差分模拟得到粘弹介质情况下的勒夫波单炮记录,并从中提取对应的频散曲线。通过理论模型提取得到频散曲线与理论频散曲线相对比,证明了本文频散曲线计算的正确性,并讨论了粘弹性介质对勒夫波频散曲线的影响,介质的粘弹性会导致勒夫波相速度的高频极限要比完全弹性介质的相速度略高。然后,通过最小二乘法反演,验证了算法程序的稳定性和可行性,结果表明采用粘弹介质频散曲线反演所得横波速度精度更高,最后通过野外实际数据反演结果进一步验证了本文方法的有效性和实际应用效果。At present,the geological situation of seismic exploration is becoming more and more complicated.With the continuous development of seismic exploration,especially for viscoelastic media,the technical requirements for surface wave exploration are getting higher and higher.Love wave refers to the horizontal polarization shear wave in the surface layer after repeated reflections at the boundary of the surface layer.Love wave detection is one of the shallow surface detection method.It is very convenient and has high detection precision.Therefore,the study of Love wave has important theoretical and practical significance.In this paper,the Love wave single shot record is simulated by high order finite difference method in the case of horizontal layered complex geological.The comparison of the dispersion curves with the theoretical dispersion curves proves that the method proposed in this paper is correct.The influence of the viscoelastic medium on the Love wave dispersion curve is also discussed.Then,the least squares inversion is used to verify this conclusion.This paper provides a more complete theoretical basis for the high-precision surface wave inversion method.Finally,the field data inversion results show that the proposed method is effective and practicable.

关 键 词：粘弹介质 勒夫波 频散曲线 

分 类 号：P631.4[天文地球—地质矿产勘探]