THE EFFECT OF CRACK PARAMETERS ON ATTENUATION ANISOTROPY: NUMERICAL MODELING

doi:10.3969/j.issn.0253-4967.2011.03.018

SEISMOLOGY AND GEOLOGY ›› 2011, Vol. 33 ›› Issue (3): 693-705.DOI: 10.3969/j.issn.0253-4967.2011.03.018

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THE EFFECT OF CRACK PARAMETERS ON ATTENUATION ANISOTROPY: NUMERICAL MODELING

CAI Xiao-gang

Institute of Crustal Dynamic,China Earthquake Administration,Beijing 100085, China

Received:2011-04-02 Revised:2011-07-01 Online:2011-09-29 Published:2011-12-16

裂隙参数对衰减各向异性影响的数值模拟

蔡晓刚

中国地震局地壳应力研究所, 北京 100085

作者简介:蔡晓刚,男,1979年生,2009年在北京大学获固体地球物理专业博士学位,助理研究员,主要从事各向异性地震波激发和传播研究,E-mail: carlos2022@sina.com。
基金资助:
中国地震局地壳应力研究所基本科研业务专项(ZDJ20101、ZDJ200911)和国家自然科学基金(41104026)共同资助。

Abstract

Abstract:

Propagation through stress-aligned fluid-filled cracks and other inclusions has been claimed to be cause of azimuthal anisotropy observed in the crust and upper mantle.This paper has examined the behavior of seismic waves attenuation caused by the internal structure of rock mass,and in particular,the internal geometry of the distributions of fluid-filled openings.So a systematic research on crack parameters' effects,such as crack density,crack aspect ratio(the ratio of crack thickness to crack diameter),pore fluid properties(particularly pore fluid velocity),V_P/V_S ratio of the matrix material and seismic wave frequency on attenuation anisotropy has been conducted based on Hudson's crack theory.The result shows that the crack density,aspect ratio,material filler,seismic wave frequency and P-wave and shear wave velocity in the background of rock mass,especially the frequency, have great effects on attenuation curves.The numerical research can help us know the effects of crack parameters and it is a good supplement for laboratory modeling.However,attenuation is less well understood because of the great sensitivity of attenuation to the details of the internal geometry.Some small changes in the characteristics of pore fluid viscosity,pore fluids containing gas and liquid phases and pore fluids containing clay can each alter attenuation coefficients by orders of magnitude.So some parameters controlling attenuation are needed to make reasonable estimation,and anisotropic attenuation is worth studying further.

Key words: equivalent media theory, crack density, attenuation anisotropy, quality factor

摘要：

理论、观测和实验均证实,在地壳和上地幔存在对应力变化敏感的直立裂隙,在整体上呈现方位各向异性。在Hudson裂隙理论基础上,系统全面地数值模拟了裂隙介质几何、物性和弹性波频率等参数对各向异性衰减的影响。结果显示,裂隙密度、裂隙纵横比、泊松比、裂缝填充物、弹性波频率和未破裂岩石母体纵横波速度等对各向异性衰减有着显著影响,尤其是频率对衰减曲线的影响最大。各向异性衰减的数值模拟有助于了解裂隙参数对各向异性衰减的影响,此外,对物理实验的模拟是一个有益的补充。

关键词: 等效介质理论, 裂隙密度, 各向异性衰减, 品质因子

CLC Number:

P315.3⁺1

CAI Xiao-gang. THE EFFECT OF CRACK PARAMETERS ON ATTENUATION ANISOTROPY: NUMERICAL MODELING[J]. SEISMOLOGY AND GEOLOGY, 2011, 33(3): 693-705.

蔡晓刚. 裂隙参数对衰减各向异性影响的数值模拟[J]. 地震地质, 2011, 33(3): 693-705.

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THE EFFECT OF CRACK PARAMETERS ON ATTENUATION ANISOTROPY: NUMERICAL MODELING

裂隙参数对衰减各向异性影响的数值模拟

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