黏弹性EDA介质中地震波传播特征弱各向异性近似研究  

Study of weak anisotropy approximation of seismic wave propagation characteristics in viscoelastic EDA

作　　者：何现启 张清 彭凌星 朱自强[3] 

机构地区：[1]湖南省交通规划勘察设计院有限公司,长沙410008 [2]湖南省高速公路建设开发总公司,长沙410001 [3]中南大学地球科学与信息物理工程学院,长沙410083

出　　处：《地球物理学进展》2018年第1期211-218,共8页Progress in Geophysics

基　　金：国家自然科学基金项目(41174061)资助,致谢 感谢审稿专家提出的修改意见和编辑部的大力支持!

摘　　要：本文主要研究了黏弹性HTI和EDA介质中地震波的波动参数(包括相速度、慢度、偏振向量和群速度),并基于摄法,推导了P、SV、SH波波动参数的弱各向异性近似公式.文章提出了慢度向量的三种定义形式,分析对比了各种定义方法在求解christo-ffel方程时的具体方法,指出特殊分量法为各向异性黏弹性介质提供了一种研究均匀和非均匀波的更简单、使用更普遍的方法.基于特殊分量法,通过求解christoffel方程,推导出黏弹性HTI介质中均匀、非均匀波的精确相速度、慢度和群速度计算公式,并通过模型计算研究了SH波的相速度特征及其随相角和不均匀参数D的变化规律,结果表明参数D对地震波的相速度大小有一定影响,但对其方位特性无影响,在EDA介质中相速度随方位角变化的规律仍然可指示介质的对称轴方向和裂隙的走向.基于摄动法,以弹性EDA介质为背景介质,通过模型计算对均匀SH波的近似公式的正确性和精度进行验证,结果证明其最大相对误差为1.15%.This paper studies the wave parameter（ including the phase velocity,slowness,group velocity and polarization vector） of seismic wave in viscoelastic HTI and EDA medium,and based on perturbation method,weakly anisotropic approximation formula of P,SV,SH wave parameters is derived. Three different slowness vector defined forms are present,the features of various definitions for methods in solving christoffel equations is analyzed and compared,and it is pointed that special component method is the simpler, universal approach to study homogeneous and inhomogeneous wave in anisotropic viscoelastic media.Based on a special component method,the expression equation of accurate phase,slowness,group velocity of homogeneous and inhomogeneous wave in viscoelastic HTI medium is derived by solving the christoffel equation,and characteristics of phase velocity of SH wave and it＇s variation with phase angle and inhomogeneous parameter D is studied by model calculation. Results show that parameter D affects the magnitude of the phase velocity of seismic waves,but has no effect on its orientation properties,the variation of phase velocity with azimuth still indicates the symmetry axis direction and fractures trend in EDA media.Based on the perturbation method（ elastic EDA media is background medium）, the correctness and accuracy of approximation formula for homogeneous SH wave is verified by model calculation,the result shows that the maximum relative error is 1. 15%.

关 键 词：黏弹性 EDA介质 相速度 均匀波 非均匀波 

分 类 号：P631[天文地球—地质矿产勘探]