求解弹性波方程的辛RKN格式   总被引：2，自引：2，他引：0       下载免费PDF全文

刘少林  李小凡  汪文帅  朱童 《地球物理学报》2015,58(4):1355-1366

将弹性波方程变换至Hamilton体系,构造适用于弹性波模拟的高效显式二阶辛Runge-Kutta-Nystrm(RKN)格式,运用根数理论得到此格式的阶条件方程组.通过给定系数的限定条件,得到方程的对称解.为了使时间离散误差达到极小,提出数值频率与真实频率比较,通过Taylor展开,得到关于辛系数的限定方程,求解方程组得到最小频散辛RKN格式.对比分析时间演进方程的稳定性,得到使库朗数达到极大值的限定方程,求解方程组得到最稳定辛RKN格式.发现此两种格式为同一格式.新得到的辛RKN格式不依赖于空间离散方法,为了对比的需要,选取有限差分法进行空间离散.在频散、稳定性分析中,与常见辛格式对比,从理论上分析了本文提出的格式在数值频散压制、稳定性提升等方面的优势,数值实验进一步证实了理论分析的正确性.  相似文献   

The dynamics of waves interacting with the Equatorial Undercurrent     

A Constantin  R.S. Johnson 《地球物理与天体物理流体动力学》2015,109(4):311-358

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The asymmetric elastic wavefields in a model comprising a liquid layer overlying an anisotropic solid seabed due to an arbitrary source within the solid     

《Applied Ocean Research》2017

The asymmetric three-dimensional radiation pattern and resultant elastodynamic response of stress waves in a model comprising a compressible water column overlying a transversely isotropic seabed in which a time-harmonic source acts is theoretically investigated. The use of potential functions, the Hankel transform, and a Fourier series expansion are adopted to deal with the equations of motion for both media. Closed-form integral expressions are developed for the potentials and the stress/displacement components. The expressions and introduced procedure are sufficiently flexible to incorporate various types of source loads. To evaluate the field quantities, the residue method and a robust integration scheme are utilized to handle the poles and branch points within the integrand. Any possible number of dispersive propagation modes are taken into account in the integral evaluation. The deduced velocity dispersion curves depict the characteristics of the various modes. They also indicate the existing singular points (poles) for a specific dimensionless frequency and the surface wave type associated with each pole. Numerical results are presented for the hydrodynamic pressure and displacement in the liquid layer and stress and displacement components in the solid seabed due to distributed and concentrated source excitations. The formulation and the numerical scheme are valid for calculating the wavefield anywhere within the model including both far- and near-field effects. The sensitivity of the results to different parameters is also analyzed. Both analytical and numerical comparisons with existing solutions for simpler cases are made to confirm the validity of the results. The results are especially useful in seismic hazard assessment of submarine earthquakes, landslides, and tsunamis. They can also be extended to deal with the fluid-solid-structure interaction problems.  相似文献   

X射线荧光光谱法测定重晶石中的硫酸钡方法研究   总被引：1，自引：0，他引：1  

陈景伟  宋江涛  陈朝阳 《岩矿测试》2017,36(4):382-387

应用XRF可快速测定重晶石中钡元素的总量,但当测定硫酸钡含量时,由于样品中的碳酸钡计入钡量造成硫酸钡的测定结果不准确,铜、铅、锌等有色金属元素对熔样坩埚会造成损害,需要进行酸处理除去碳酸钡、铅等干扰。而样品经酸处理后不同样品的剩余量不同,造成熔剂与样品的比例不确定,也不能准确测定硫酸钡的含量,因此保证熔剂与样品比例一致是解决该问题的关键。本文优化了样品前处理、熔片制样和仪器工作条件,将一定量样品以10%盐酸和10%硝酸溶解,过滤除去碳酸钡、硫酸钙及铜、铅、锌等有色金属元素,未溶解样品在700℃下灼烧后以氧化铝补充到原取样量,实现了熔剂与样品比例一致,再以硝酸铵作氧化剂,溴化锂和碘化铵作脱模剂,1075℃熔融制片,即可用XRF准确测定硫酸钡的含量。本方法的相对标准偏差(RSD)小于0.4%,检出限为72μg/g,较ICP-OES等方法的检测周期短、干扰元素少,提高了测试效率和分析质量。  相似文献   

黏弹性与弹性介质中Rayleigh面波特性对比研究   总被引：8，自引：7，他引：1       下载免费PDF全文

高静怀  何洋洋  马逸尘 《地球物理学报》2012,55(1):207-218

Rayleigh面波的频散特性可以用来研究地表浅层结构. 本文使用时域有限差分法来模拟复杂黏弹性介质中的Rayleigh面波,研究了Q值对面波频散特性的影响.文中采用旋转交错网格有限差分,以非分裂卷积形式的完全匹配层为吸收边界,推出了求解二阶位移-应力各向同性黏弹性波动方程的数值方法.为了检验数值解的精度,首先将简单模型的正演结果与解析解对比,验证了方法的正确性;然后模拟了横向缓变层状介质和含有洞穴的介质中的面波,对弹性和黏弹性介质中的面波的频散特性进行对比分析.模拟结果表明浅层Q值对面波的频散特性有显著的影响;强吸收情况下,高阶面波的能量相对低阶面波能量显著增强.  相似文献   

槽波层析成像方法在煤田勘探中的应用——以河南义马矿区为例   总被引：9，自引：4，他引：5       下载免费PDF全文

王伟  高星  李松营  乐勇  胡国泽  历玉英 《地球物理学报》2012,55(3):1054-1062

在地下煤田的开发中,工作面内的小构造、异常体、煤层厚度变化等是需要解决的关键问题,而槽波探测则为这些问题的解决提供了重要的物探方法.本文对河南义马矿区11061工作面进行槽波透射法测量,在巷道显示的煤层厚度变化为1.5~8 m,从理论频散曲线分析速度与厚度关系,确定125 Hz频率槽波主要用于观测厚度约为2~5 m的煤层厚度变化;有效提取了684个频散曲线,并分别拾取了125 Hz时槽波群速度与走时,采用走时层析成像方法获得工作面内煤层速度、厚度以及高应力区分布特征,回采验证了结果的正确性.  相似文献   

利用噪声记录估计福建地区中上地壳体波速度结构     

李军  金星  鲍挺  林树  韦永祥  张红才 《中国地震研究》2012,26(3):310-320

In this paper,the dispersion curves of the Rayleigh wave and Love wave were extracted from the seismic noise records of 25 broadband stations of the Fujian Seismic Network, and inverted for the lithosphere velocity structure. Furthermore,the velocity model was verified by the seismic explosion observations. Our results indicate that the resolution of the lithosphere velocity structure obtained by this method is good in the shallow part,but in the deep part,inversion accuracy for the wave velocity structure is low,which is caused mainly by the small inter-station distance chosen in the paper. Thus the wave dispersion curves have high accuracy in the short-period part,but the warp of the wave dispersion curve in long-period part is large. Considering the results from both the noise inversion and the traditional inversion,we finally present a new velocity model,and the theoretical travel time calculated with the new model matches the explosion travel time very well.  相似文献   

Application of passive source surface-wave method in site engineering seismic survey          下载免费PDF全文

Chaofan Wang  Jian Zhang  Lihui Yan  Hui Liu  Dong Zhao 《地震科学（英文版）》2014,27(1):101-106

Site engineering seismic survey provides basic data for seismic effect analysis. As an important parameter of soil, shear-wave velocity is usually obtained through wave velocity testing in borehole. In this paper, the passive source surface-wave method is introduced into the site engineering seismic survey and practically applied in an engineering site of Shijingshan District. By recording the ubiquitous weak vibration on the earth surface, extract the dispersion curve from the surface-wave components using the SPAC method and obtain the shear-wave velocity structure from inversion. Over the depth of 42 m underground, it totally consists of five layers with interface depth of 3.31, 4.50, 7.23, 17.41, and 42.00 m; and shear-wave velocity of 144.0, 198.3, 339.4, 744.2, and 903.7 m/s, respectively. The inversion result is used to evaluate site classification, determine the maximum shear modulus of soil, provide basis for further seismic hazard analysis and site assessment or site zoning, etc. The result shows that the passive source surface-wave method is feasible in the site engineering seismic survey and can replace boreholes, shorten survey period, and reduce engineering cost to some extent.  相似文献   

混合ADI-FDTD亚网格技术在探地雷达频散媒质中的高效正演   总被引：4，自引：4，他引：0       下载免费PDF全文

冯德山  陈佳维  吴奇 《地球物理学报》2014,57(4):1322-1334

提出混合ADI-FDTD亚网格技术开展频散介质GPR正演,即在物性参数变化剧烈局部区域采用细网格剖分ADI-FDTD计算,其他的区域采用粗网格剖分常规FDTD计算,ADI-FDTD突破了CFL条件的限制,可选取与粗网格一致的大时间步长,有效地提高了计算效率.本文首先基于Debye方程,推导了粗网格FDTD及细网格ADI-FDTD频散介质差分格式,着重对粗细两种网格结合的场值交换方式进行了深入探讨,给出了该算法的计算流程.然后以一个薄层模型为例,分别应用粗网格、细网格、混合ADI-FDTD亚网格算法对该模型进行正演,计算资源的占用及模拟精度说明了混合ADI-FDTD亚网格算法的优势.最后,建立频散介质与非频散介质的组合模型,应用3种方法对该模型进行正演,对比3种方法优劣,分析雷达剖面中非频散介质及频散介质中波形特征,有效地指导雷达资料的精确解释.  相似文献   

地震波频散效应与反Q滤波相位补偿   总被引：2，自引：0，他引：2       下载免费PDF全文

张固澜  贺振华  王熙明  张建军  张彦斌  李飞 《地球物理学报》2014,57(5):1655-1663

本文以Futterman提出的地震波振幅衰减和相速度频散表达式为基础,从井震匹配的角度出发,推导了不进行反Q滤波、仅反Q滤波振幅补偿、仅反Q滤波相位补偿,以及反Q滤波相位与振幅同时补偿四种情况下,地震波速度频散与相速度及地震记录振幅谱间的表达式,并从理论上说明了反Q滤波相位补偿的必要性.通过相同观测系统,炸药震源和可控震源分别激发采集的零偏移距VSP资料实例,验证了本文所推导的速度频散表达式的合理性;通过井震标定实例,进一步说明了反Q滤波相位补偿,可有效消除地震子波速度频散,提升地面地震资料与零偏移距VSP走廊叠加剖面的匹配度,最终提高地震资料成果的可信度.  相似文献