Maslov面波理论地震图          下载免费PDF全文

朱良保  曾融生 《地球物理学报》1995,38(5):608-617

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．  相似文献   

数字地震数据尾波Q值计算实用软件     

华正兴  高龙生 《地震地磁观测与研究》1995,16(1):35-41

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。  相似文献   

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   总被引：5，自引：0，他引：5       下载免费PDF全文

李国敏  陈崇希 《地球科学》1995,4(4)

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。  相似文献   

Single Scattering Theory Versus Numerical Modelling In 2-D Random Media   总被引：1，自引：0，他引：1  

M. Roth  M. Korn 《Geophysical Journal International》1993,112(1):124-140

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Synthesis of coda waves in layered medium   总被引：3，自引：0，他引：3  

Chien-Ying Wang  Robert B. Herrmann 《Pure and Applied Geophysics》1988,128(1-2):7-42

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各向异性介质中地震波前面的偏微分方程   总被引：7，自引：0，他引：7       下载免费PDF全文

张中杰  滕吉文 《地球物理学报》1994,37(2):220-227

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．  相似文献   

The Direct Shear Strength and Dilatancy of Sand–gravel Mixtures     

Alessandro Simoni  Guy T. Houlsby 《Geotechnical and Geological Engineering》2006,24(3):523-549

A total of 87 direct shear tests in a large direct shear-box apparatus have been used to investigate the strength and dilatancy of sand–gravel mixtures. This paper focuses on the differences in behaviour between a silica sand (yellow Leighton Buzzard sand) and sand–gravel mixtures obtained by adding fractions of two kinds of gravel to the sand. The purpose is to find a relation between the grain-size characteristics of the materials and the shearing resistance. Experimental results are analysed in terms of the frictional and dilatant contributions to the strength of mixtures as a function of their relative density, and are compared with dilatancy theories and empirical equations. The addition of gravel to the mixtures, even at low fractions (less than 0.1 by volume), causes an increase in peak friction angle (Φ ′_peak) which results both from higher dilatancy at failure (ψ_max) and higher constant volume friction angle (Φ ′_cv). Use of the minimum voids ratio (e_min) of the materials allows the data for the two families of mixtures to be normalized and interpreted in terms of Φ ′_cv and the ratio (Φ ′_peak − Φ ′_cv)/ψ_max. The relationships between relative density (D_r), ψ_max and Φ ′_peak − Φ ′_cv are only partly explained on a physical basis, so we develop empirical equations to predict the peak shear resistance of sand–gravel mixtures (up to gravel contents of 0.5) on the basis of easily measurable quantities. Such equations constitute a practical tool to overcome the problems arising from the impracticality of testing coarse material in the standard shear-box apparatus.  相似文献   

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

Jian-Fei Lu  Dong-Sheng Jeng  Wei-Dong Nie 《Computers and Geotechnics》2006,33(8):404-418

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.  相似文献   

Non-uniform granular pile–mat foundations: analysis and model tests     

J. T. Shahu 《Geotechnical and Geological Engineering》2006,24(4):1065-1087

Granular piles are commonly used to improve bearing capacity and reduce settlements of soft soil in coastal and lowland areas. Due to various reasons, granular piles tend to acquire a non-uniform tapered-down cross-section in actual construction process. In this paper, a simple theoretical approach to predict deformation behaviour of soft ground reinforced with non-uniform granular pile–mat system is presented. A small-scale experimental set-up is fabricated in the laboratory and tests performed. Results predicted by the proposed approach compare well with the laboratory tests, and the field tests and other numerical test results available in literature. A parametric study has been carried out to evaluate the relative influence of granular mat thickness and relative stiffness on various responses of non-uniform granular piles.  相似文献   

均匀和梯度介质中等时面(线)的几何特征分析     

YE Yun-fei 《吉林大学学报(地球科学版)》2006,(Z2)

等时面是地震波时间场的等值面,是Kirchhoff型数值模拟及Kirchhoff型偏移与反偏移的数据叠加或数据分布曲面,其几何形状和局部曲率对于Kirchhoff型真振幅偏移和反偏移中的加权函数计算和成像效果具有重要的影响。本文推导了均匀和梯度介质中的等时线公式并计算了二维均匀和梯度介质中等时线的几何特征。  相似文献