Maslov面波理论地震图

研究了横向非均匀介质中的Ｍａｓｌｏｖ面波渐近理论，在横向弱非均匀介质的假设下，介质的纵向非均匀性反应在局部本征函数中，以局部本征函数近似真本征函数是射线理论的直接推论．由此，三维结构下的面波计算退化为准二维问题．由于本文方法属于慢度法，面波的频散使得在一般情况下得不到与体波ＷＫＢＪ方法相似的褶积结果；在震源函数为高斯波包的假设下，得出了与二维体波Ｍａｓｌｏｖ理论图形式上完全相同的褶积结果．还讨论了吸收介质中的面波波包理论图计算，最后结果与二维体波吸收介质中的结果相似．     

数字地震数据尾波Q值计算实用软件

利用高精度的数字地震尾波记录来测定一定区域范围内或地震活动区内的介质品质因素Ｑ，是一项非常有意义的工作。本文介绍了一套方法上较完备和相对规范化的尾波Ｑ值计算软件，运用中国数字化地震台网（ＣＤＳＮ）记录给出计算实例。     

空隙介质水动力弥散尺度效应的分形特征及弥散度初步估计

通过时空隙介质中水动力弥散尺度效应近期研究成果的总结和分析，阐述了不同尺度下空隙介质的空间非均质的自相似性，提出了水动力弥散的尺度效应在统计意义上具有分形特征，按计算方法（解析模型与数值方法）与岩性特征（孔隙介质与非孔隙介质）及计算模型维数的不同，对世界范围内所收集到的百余个纵向弥散度数据求出了尺度效应的分维数并进行了分析与讨论，为地下水污染模型研究提供了一种参数的初步估计方法。     

Ray theory of modulated body waves in inhomogeneous viscoelastic media

Ray theory based upon real rays is presented for high frequencyP andS waves in continuously inhomogeneous isotropic linear media. Simple explicit formulae for the polarization anomalies described by higher order terms of the ray asymptotic expansions are considered.     

Complex rays applied to wave propagation in a viscoelastic medium

In order to trace a ray between known source and receiver locations in a perfectly elastic medium, the take-off angle must be determined, or equialently, the ray parameter. In a viscoelastic medium, the initial value of a second angle, the attenuation angle (the angle between the normal to the plane wavefront and the direction of maximum attenuation), must also be determined. There seems to be no agreement in the literature as to how this should be done. In computing anelastic synthetic seismograms, some authors have simply chosen arbitrary numerical values for the initial attenuation angle, resulting in different raypaths for different choices. There exists, however, a procedure in which the arbitrariness is not present, i.e., in which the raypath is uniquely determined. It consists of computing the value of the anelastic ray parameter for which the phase function is stationary (Fermat's principle). This unique value of the ray parameter gives unique values for the take-off and attenuation angles. The coordinates of points on these stationary raypaths are complex numbers. Such rays are known as complex rays. They have been used to study electromagnetic wave propagation in lossy media. However, ray-synthetic seismograms can be computed by this procedure without concern for the details of complex raypath coordinates. To clarify the nature of complex rays, we study two examples involving a ray passing through a vertically inhomogeneous medium. In the first example, the medium consists of a sequence of discrete homogeneous layers. We find that the coordinates of points on the ray are generally complex (other than the source and receiver points which are usually assumed to lie in real space), except for a ray which is symmetric about an axis down its center, in which case the center point of the ray lies in real space. In the second example, the velocity varies continuously and linearly with depth. We show that, in geneneral, the turning point of the ray lies in complex space (unlike the symmetric ray in the discrete layer case), except if the ratio of the velocity gradient to the complex frequency-dependent velocity at the surface is a real number. We also present a numerical example which demonstrates that the differences between parameters, such as arrival time and raypath angles, for the stationary ray and for rays computed by the above-mentioned arbitrary approaches can be substantial.     

地震波场正演模拟中的有限单元方法

本文介绍了地震波场正演模拟中的有限单元方法。首先从粘弹性波动理论出发,推导了满足粘弹性介质的有限元方程,其次用不含阻尼矩阵的有限元方程模拟了地震记录。地表实例是自由界面的瑞雷面波。VSP记录有水平层、倾斜层;有零井源距和非零井源距;有线状和对称震源。 在程序中采用了超压缩存贮和分块计算措施,对降低有限元法要求计算机内存和运算速度的苛刻条件上做了有益的尝试。     

各向异性介质中地震波前面的偏微分方程

从含２１个弹性参数的各向异性介质中关于位移分量ｕ_ｘ、ｕ_ｙ与ｕ_ｚ的偏微分波动方程组出发，通过假定平面波位移函数解，导出准Ｐ波、准ＳＶ波与准ＳＨ波的波前面偏微分控制方程，进而对各类特殊各向异性介质（横向各向同性介质、椭圆及立方体各向异性介质）中地震波前面偏微分方程进行了讨论．以上结果为研究各向异性介质中地震波传播规律以及进行正、反演研究奠定了理论基础．     

Dynamic response of a pile embedded in a porous medium subjected to plane SH waves

In this paper, the frequency domain dynamic response of a pile embedded in a porous medium subjected to SH seismic waves is investigated. The surrounding porous medium of the pile is described by Biot’s poro-elastic theory, while the pile embedded in the porous medium is treated as a beam and described by a beam vibration theory. Using the Hankel transformation method, the fundamental solution for a half-space porous medium subjected to a horizontal circular patch load is established. According to the fictitious pile methodology, the second kind of Fredholm integral equation for the pile is established in terms of the obtained fundamental solution and free wave field. The solution of the integral equation yields the dynamic response of the pile to plane SH waves. Numerical results indicate that the parameters of the porous medium, the pile and incident waves have considerable influences on the dynamic response of the pile and the porous medium.