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随着国家电网建设规模的不断扩大,越来越多的高压直流输电工程陆续投入使用,对线路两侧的地磁观测资料造成了不可避免的影响。目前有5条高压直流输电线路对甘肃地磁台站的观测造成一定程度的干扰。通过单台及多台观测资料对比的方法,识别高压直流输电线对地磁观测资料的影响,研究干扰特征,对正确预处理观测资料有重要的意义。结果表明:①高压直流输电对地磁Z分量影响明显,D、H分量不明显;②对地磁观测影响产生的形态主要表现为方波型、缓变型、梯形型、复合型等。通过总结高压直流输电对地磁观测资料影响特征及形态,有助于正确预处理观测资料及为今后实现计算机自动化处理提供依据。 相似文献
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2009年12月,甘肃天水、陕西乾陵等地磁台Z分量观测差值出现台阶式异常变化,同期陕西关中地区宝鸡、乾陵、周至等台站地电场观测也出现同步异常变化.经调查落实,确认此变化是由宝鸡—德阳±500kV直流输电工程试运行引起的.高压直流输电是近年来新出现的地磁观测中的一类干扰异常.根据对宝鸡—德阳高压直流输电线路邻近区域各地磁台站实际观测资料的分析,并结合安培定理和毕奥-萨伐尔定律计算了理想状态下高压直流输电对地磁观测的影响.结果表明,理论值与实际观测值基本相符,从而从机理上解释了高压直流输电对地磁观测影响的原因.由于计算时没有考虑不同地磁观测系统的差异和地下电性结构等因素的影响,因此计算方法有待进一步完善. 相似文献
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近年来,承德地球物理台网观测数据受到高压直流输电和车辆等场地环境干扰。以承德和丰宁地震台FHD-2B质子矢量磁力仪观测数据为基础,从影响分量、多台站对比、查询方式等识别干扰源,分析2种影响因素的特点,结果显示:①高压直流输电主要影响垂直分量Z;车辆干扰时,磁偏角D、垂直分量Z、水平分量H均可能受到影响;②高压直流输电会影响沿线多个台站,且曲线畸变在时间上具有同步性;车辆干扰一般只影响附近单个台站;③高压直流输电影响可在国家地磁台网中心网站查询;车辆干扰可通过查看监控、询问门卫、每日巡查场地等方式核实。 相似文献
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高压直流输电线路对地磁观测的干扰幅度大,随意性大.泾县地震台地磁观测目前受到附近穿行的多条高压直流输电影响,且无法避免.通过对泾县地震台观测资料分析,就高压直流输电对地磁观测的干扰原理和一些识别的方法有一定认识,并掌握有效剔除方法. 相似文献
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全国范围内越来越多的高压直流输电工程投入运行,其中5条线路运行对陕西地磁观测造成一定干扰。统计2014年1月-2018年6月陕西地磁观测受高压直流输电影响情况,分析各地磁观测台受高压直流输电线路影响的特征,提出判别直流输电干扰线路的方法和应对高压直流输电干扰的建议。 相似文献
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地磁观测要达到为国民经济、科学研究和地震预报服务的目的 ,必须保证观测资料的质量。泾县台目前仅有磁绝对值观测 ,使用 FG-861质子旋进磁力仪作北京时 2 1时 0 0分定点观测 ,测量地磁场总强度 F和垂直分量 Z。 1 997年 3月 2 2日 ,泾县台地磁垂直分量 Z突跳1 0 n T,而安徽省的蒙城、蚌埠、金寨等台的垂直分量均变化平稳 ,蒙城台三分量磁照图亦变化平稳 ,没有磁扰。毗邻的江苏省溧阳、南京台的垂直分量变化亦在 1～ 3n T以内。从1 995年 1 0月到 1 996年 1 0月的泾县台与蒙城、上海、武昌台的观测值对比图上也可看出 ,泾县台曾多次出现… 相似文献
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本文研究2017—2022年湖北省地磁观测受高压直流输电干扰的情况,发现目前有14条线路造成干扰,干扰集中在新线路投运初期,年均受干扰天数约105天。此外,探讨了高压直流输电线路的发展特点和湖北地磁台站布局的合理性,归纳了缓变的4种基本形态,明确了各种干扰形式的处理思路和步骤,发现同一线路对不同台站的干扰幅度,以及对同一台站地磁Z、F分量干扰幅度均线性相关。研究结论有助于提高地磁高压直流干扰数据处理的精度和效率,为进一步开发自动化处理算法积累了理论基础。 相似文献
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Electromagnetic induction of a three-dimensional conductivity inhomogeneity in the two-layered earth
Summary The calculation of the elements of Green's tensor function is presented for solving the problem of the electromagnetic induction by means of a vector integral equation. A two-layered Earth is considered as the medium, the surface layer including a three-dimensional conductivity inhomogeneity. Use is made of the boundary condition requiring the vertical component of the electric current to be zero at the Earth's surface which partly simplifies the theoretical computation. Long-period asymptotics of the individual complicated functions, occurring in Green's tensor function as well as in the tensor function required to calculate the components of the anomalous magnetic field at the surface of the halfspace, were effected. With the aid of these asymptotics one can obtain estimates of the functions occurring in the theoretical analysis of the problem. 相似文献
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Robert E. Dickinson 《Pure and Applied Geophysics》1969,72(1):198-203
Summary The theory of atmospheric tides is derived from the meteorological primitive equations by means of a perturbation expansion in Rossby number. Separation of the system for the first order variables into the standard horizontal and vertical structure equations of tidal theory is effected. 相似文献
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For a low-level geomagnetic satellite survey, for which the motion of the satellite converts spatial variation into temporal variation, the limit on accuracy may well be background temporal fluctuations. The sources of the temporal fluctuations are current systems external to the Earth and include currents induced in the Earth due to these sources. The internal sources consist primarily of two components, the main geomagnetic field with sources in the Earth's core and a crustal geomagnetic field.Power spectra of the vertical geomagnetic field internal component that would be observed by a spacecraft in circular orbit at various altitudes, due to satellite motion through the spatially varying geomagnetic field, are compared to power spectra of the natural temporal fluctuations of the geomagnetic field vertical component (natural noise) and to the power spectrum for typical fluxgate magnetometer instrument noise. The natural noise is shown to be greater than this typical instrument noise over the entire frequency range for which useful measurements of the geomagnetic field may be made, for all geomagnetic latitudes and all times. Thus there would be little benefit in reducing the instrument noise below the typical value of 10?4 gamma2 Hz?1 plus a 1/f component of 10 milligamma rms decade?1.For a given satellite altitude, there is a maximum frequency above which the natural noise is greater than the power spectrum of the crustal geomagnetic field vertical component. Below this maximum frequency, the situation is reversed. This maximum frequency depends on geomagnetic latitude (and to a lesser extent on time of day and season of year), being lower in the auroral zone than at lower latitudes. The maximum frequency is also lower at higher satellite altitudes. The maximum frequency determines the spatial resolution obtainable on a magnetic field map. The spatial resolution (for impulses) obtainable at low latitudes for a 100-km satellite altitude (possibly achievable by tethering a small satellite at this altitude to a space vehicle at a higher altitude) is 60 km, while at the auroral zone the obtainable spatial resolution is 100 km. At the higher satellite altitude of 300 km the obtainable spatial resolution is 230 km at low latitudes and 530 km at the auroral zone. At 500-km satellite altitude, the obtainable spatial resolution is 500 km at low latitudes, while maps cannot be made at all for the auroral zone unless the data are selected for “quiet” days.For the lower satellite altitudes, greater spatial resolution can be obtained than at higher altitudes. Furthermore since the crustal geomagnetic field power spectrum is larger at lower altitudes, the relative error due to the natural noise is less than for higher altitudes. 相似文献
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Measurements of ground motions during past earthquakes indicate that the vertical acceleration can reach values comparable to horizontal accelerations or may even exceed these accelerations. Furthermore, measurements of structural response show the possibility of significant amplification in the response of bridges in the vertical direction that can be attributed to the vertical component of ground motion. In this study, the relative importance of the vertical component of ground motion on the inelastic response of R/C highway bridges is investigated. Particular emphasis is placed on modelling of the deck and piers to account for complex loading histories under combined vertical and horizontal earthquake motions. Analyses of actual bridges indicate that, in general, the vertical motion will increase the level of response and the amount of damage sustained by a highway bridge. Vertical motion generates fluctuating axial forces in the columns, which cause unstability of the hysteresis loops and increase the ductility demand. Furthermore, vertical motion can generate forces of high magnitude in the abutments and foundations that are not accounted for by the current seismic design guidelines. Thus, it is important to consider this component of the ground motion in the design of highway bridges, especially for those located in regions near seismic faults. 相似文献
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波形梯度法是一种全新的台阵数据处理技术,该方法利用子台阵中的波形差异可以得到一些基本的地震波传播参数.本文首次将其应用于美国中东部地震台阵面波的三分量研究当中.首先通过垂向分量的面波进行波形梯度分析,得到垂直分量面波的相速度、传播方向、几何扩散和辐射花样.再通过垂向分量得到的传播方向进行坐标旋转,从而得到了径向分量以及切向分量的面波,再将其应用于波形梯度分析,分别得到径向分量以及切向分量面波的相速度、传播方向、几何扩散和辐射花样.利用2012年8月27日发生在中美洲西海岸地震事件的三分量地震数据的面波波形得到的结果显示,在相同周期,研究区域的三个分量面波的相速度分布横向差异显著.切向分量面波的相速度分布特征差异较大,可能是由于径向各向异性造成的.三个分量的传播方向变化都不大,且切向分量的传播方向变化大于垂直分量与径向分量,说明地震波的切线分量在传播过程中受到的影响更大,同时还可以看出传播方向的变化呈现出条带状的特征.几何扩散和辐射花样都是与地震波的振幅项有关的信息,三个分量的几何扩散特征基本一致.但是由于切向分量传播方向变化相对较大,可能导致了切向分量面波的辐射花样有所差异. 相似文献
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井下地震计波形记录的P波垂向分量存在频谱极小（spectrum null）现象,导致接收函数的结果不稳定.本文以首都圈地区为例,基于平面波入射的传播矩阵理论,发展了用于计算井下地震计的接收函数正演方法.在此基础上,分析了井下地震计波形垂向分量频谱极小现象,研究其对接收函数稳定性的影响.结果表明,井下地震计波形记录垂向分量的频谱极小开始出现的频率和地震计的埋深相关.该现象可造成反卷积提取的接收函数不稳定,且不稳定情况出现在频谱极小附近的频段,可通过选择合适的高斯因子压制其对接收函数的影响. 相似文献
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Hydrodynamic pressures and structural response of concrete gravity dams, including dam-reservoir interaction, due to the vertical component of earthquake ground motions are investigated. The response of the dam is approximated by the deformations in the fundamental mode of vibration, and the effects of deformability of bed rock on hydrodynamic pressures are recognized in the analysis. Expressions for the complex frequency response functions for the dam displacement, dam acceleration and lateral hydrodynamic force are derived. These results along with the Fast Fourier Transform algorithm are utilized to compute the time-history of responses of dams of 100, 300 and 600 ft height, with full reservoir, for different values of elastic modulus of mass concrete: 3.0, 3.5, 4.0, 4.5 and 5.0 million psi, to the vertical component of El Centro, 1940, and Taft, 1952, ground motions. It is concluded that the hydrodynamic forces caused by vertical ground motion are affected substantially by damreservoir interaction and depend strongly on the modulus of elasticity of the dam. The dam response to the vertical component of ground motion is compared with that due to the horizontal component. It is concluded that because the vertical component of ground motion causes significant hydrodynamic forces in the horizontal direction on a vertical upstream face, responses to the vertical component of ground motion are of special importance in analysis of concrete gravity dams subjected to earthquakes. 相似文献
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中国l地壳运动观测网络首期观测数据处理 总被引：6，自引：0，他引：6
介绍了中国地壳运动观测网络的布设、基准站和基本站首期观测情况。利用GAMIT和GLOBK软件对首期观测数据进行了处理，计算结果归算到ITRF97框架上。单天整体解结果表明：基线重复性NS向分量为2.28+0.87×10-9×S，EW向分量为3.67+0.82×10-9×S，高程分量为6.84+1.29×10-9×S(S为GPS站间距离，以mm为单位)。对基准网和基本网的整体平差结果表明：点位精度水平分量为2～3 mm，高程分量为3～5 mm，基准网和基本网首期观测达到了设计要求。 相似文献
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本文分析了引起强震前天文测时测纬异常现象的原因问题,认为这种异常主要是地下水活动引起垂线变化的结果.垂线变化包括重力场水平分量变化和垂直分量变化,前者可引起测时测纬异常.地下水活动的主要形式是垂直迁移,这种垂直迁移又沿着一定的水平方向传递.从测时测纬的异常形态和地下水的活动规律,可以分析出应力场变化的某些规律.地下水的这种活动,引起的重力场水平分量变化远远大于垂直分量的变化,两者的变化形式也很不同. 相似文献