不同温压下岩石弹性波速度、衰减及各向异性与组构的关系

结合岩石组构分析 ,阐述了岩石弹性波传播速度和衰减以及它们的各向异性与岩石组构之间的关系。在不同温压条件下对具有很强晶格优选方位的岩石样品的研究表明 ,随着围压的增加 ,波速和Q值均增大 ,但是在相互正交的 3个方向上 (垂直或平行于层理面及线理方向 )增大的速度并不相同 ,这与微裂隙的逐渐闭合密切相关。观测到的波速和Q值的各向异性具有不同的形成机理 ,波速各向异性主要与定向分布的微裂隙和主要矿物的晶格优选方位等构造因素有关 ;高围压下Q值各向异性与速度各向异性正好相反 ,可能是由于定向排列的矿物晶体沿不同方向其边界之间接触程度不同造成的。对岩石组构的研究不仅可以揭示岩体的变形机制、变形的动力学过程及其有关的热力学信息 ,还可以对宏观岩石的各种物理性质 ,尤其是力学特性 ,从微观机理上加以解释。文中特别强调了岩石组构分析对研究岩石物理性质的各向异性具有十分重要的意义。

RELATIONS OF ELASTIC WAVE VELOCITY AND ATTENUATION AND THEIR ANISOTROPIES TO THE FABRIC OF ROCKS UNDER DIFFERENT p-T CONDITIONS

Based on fabric analysis,the paper describes the relation of elastic wave velocity,especially its attenuation,and their anisotropies to the rocks' fabric Laboratory research on rock samples with strong lattice preferred orientation (LPO) under different pressure and temperature conditions shows that velocities and Q values increase with pressure,and the rate is different in the three orthogonal directions (normal,parallel to foliation and lineation) due to the progressive closure of microcracks The anisotropies of velocities and Q values are found to be different by nature The anisotropy of wave velocity is caused by oriented microcracks and the LPO of major minerals Under high pressures,the anisotropy of Q is reversed from that of velocity and may be due to the directional dependent increase of contact areas on the grain boundaries of the oriented minerals Rock fabric analysis is very important in the research on the anisotropy of many physical properties in rocks