基于黏弹各向异性理论的地震波场数值模拟与分析

基于Carcione黏弹各向异性理论及具有任意倾斜对称轴的横向各向同性介质(TTI)的本构关系,利用二维三分量高阶交错网格有限差分和完全匹配层边界条件对黏弹TTI介质的地震波场信息进行了数值模拟。研究发现:1改变黏弹TTI介质的弹性参数,对地震波传播造成显著影响。其中,C_(13)主要控制qS1波中质点的偏振方向,进而影响了qS1波波形和反射同相轴的形态;而C_(66)则主要控制qS2波中质点的偏振方向,从而影响了qS2波波形和反射同相轴的形态;2利用层状黏弹TTI介质进行数值模拟,可以很好地观察到拟横波在遇到反射界面时发生的横波再分裂现象;同时由于介质黏弹性的存在,导致地震波出现显著的衰减。这将为进一步研究各向异性介质中复杂的波场信息提供帮助。

Analysis of Seismic Numerical Simulation Based on Theory of Viscoelasticity and Anisotropy

Based on the Carcione viscoelasticity and anisotropy theory and constitutive relation of TTI media,this paper simulated the seismic wavefield of viscoelastic TTI media through two-dimensional,three-component high-order staggered-grid finite-difference method and PML boundary.We found that:(1)Changing the elastic parameters make huge difference to the seismic wavefield.And C13 controls the direction of polarization in qS1 wave,leading to the changing of waveform and reflection event of qS1.And C66 does have the same function to qS2.(2)After the numerical modeling of layered viscoelastic TTI media,we could obviously saw the qS wave second splitting phenomenon when the reflection surface appeared.Furthermore,due to the viscoelasticity of the TTI media,attenuation of seismic wave was observed.This research will make some theoretical foundation for further study of seismic wavefield inanisotropic media.