A combined inversion of Rayleigh wave dispersion and 2-D resonance frequencies   总被引：1，自引：1，他引：1  

D. Roten  D. Fäh 《Geophysical Journal International》2007,168(3):1261-1275

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1976年唐山大地震的孕震环境:密集地震台阵观测得到的结果   总被引：7，自引：0，他引：7  

刘启元  王峻  陈九辉  李顺成  郭飚 《地学前缘》2007,14(6):205-213

1976-07-28唐山地区发生了震惊中外的7.8级大地震。为什么在华北古老克拉通内部的唐山地区能够发生如此的大地震一直是一个令人费解的问题。是否会在唐山地区再次出现同样的破坏性地震值得认真研究。利用流动地震观测台阵数据和接收函数反演方法,我们研究了唐山地区60 km深度范围内的三维地壳上地幔速度结构。结果表明:(1)由活动断裂切割的唐山断块与周围介质存在明显差异,围限唐山断块的断裂均为超壳的活动断裂;(2)唐山大震区中上地壳具有明显的非均匀壳内低速体;(3)该地区壳幔界面表现为明显的断块式隆升,与两侧相比,唐山菱形地块下方的上地幔顶部异常隆起的高度达到10 km左右,下伏的上地幔具有异常的非均匀结构;(4)唐山大震区可能有幔源物质较大规模的侵入,形成了中、上地壳内的低速体。由于较已往的研究结果有更高的空间分辨率,我们得到了一些以往尚未发现的有关唐山地区深部结构的异常特征;(5)首都圈地区内破坏性地震发生的地点绝非偶然,它们均与其相应的深部构造背景密切有关,这为强震发生地点的预测提供了可能。根据本文结果,我们认为,1976年唐山大地震的主因源于上地幔的垂向运动变形及壳幔之间物质及能量的交换,区域水平向应力场为次要作用。这有助于解释为什么能够在我国华北古老克拉通地区发生7级以上强震,在唐山地区再次发生7级以上大地震的可能性值得给予进一步的研究和关注。  相似文献   

阵列相位激电法在内蒙古某铜矿区的应用效果     

徐宝利  林品荣  李建华 《物探化探计算技术》2007,(Z1)

简要介绍了阵列相位激电法的方法原理,阐述了该方法在内蒙古某铜矿区的试验应用效果。  相似文献   

Finite element analysis of structure-borne vibration from high-speed train   总被引：5，自引：0，他引：5  

S.H. Ju   《Soil Dynamics and Earthquake Engineering》2007,27(3):259-273

Finite element analyses were used to investigate the behavior of the building vibration induced by high-speed trains moving on bridges. The model includes the bridge, nearby building, soil and train. Finite element results indicate that trainload frequencies are more important than the natural frequencies of bridges and trains for building vibrations. If the building natural frequencies approach to the trainload frequencies, which equal an integer times the train speed over the compartment length, the resonance occurs and the building vibration will be large. Moreover, the vibration shape is similar to the mode shape of the resonance building frequency. To isolate the building vibration induced by moving trains, this paper investigates three common types of foundations, which include the extension of retaining walls, pile foundation and soil improvement around the building. Soil improvement around the building is the best way to reduce the building vibration both in horizontal and vertical directions.  相似文献   

Shinkansen high-speed train induced ground vibrations in view of viaduct–ground interaction     

Hirokazu Takemiya  Xue Cheng Bian   《Soil Dynamics and Earthquake Engineering》2007,27(6):506-520

Train viaduct behavior and nearby ground motion under the high-speed train passage have been studied in this paper. First, the findings from the field measurement alongside the high-speed Shinkansen railway in Japan are interpreted. Then, the computer simulation is made based on the soil-foundation-viaduct interaction analysis under moving axle loads. The solution method is to apply the dynamic substructure method in the frequency domain. The viaduct girders including track structure and pier supports are modeled by the three-dimensional beam-column elements. The supporting pile foundation and nearby field are discretized by the axisymmetric three-dimensional finite elements and analyzed in a semi-analytical way, with a transmitting boundary replacing the far field based on the thin layer element method. Nearby ground motion during train passage on a viaduct have been calculated by superimposing the effects from neighboring pile foundations.The main parameters affecting viaduct vibrations are discussed by taking environmental vibration into consideration. The nearby ground motion along the viaduct is recomputed by applying the above determined forces to the foundation tops. The results from numerical studies are compared with the field test data, thus proving the present simulation to be effective and reliable.  相似文献   

Comparison of Wind-tunnel and Water-channel Simulations of Plume Dispersion through a Large Array of Obstacles with a Scaled Field Experiment     

Eugene Yee  Ralph M. Gailis  Alexander Hill  Trevor Hilderman  Darwin Kiel 《Boundary-Layer Meteorology》2006,121(3):389-432

We report on measurements of the near-field dispersion of contaminant plumes in a large array of building-like obstacles at three scales; namely, at full-scale in a field experiment, at 1:50 scale in a wind-tunnel simulation, and at 1:205 scale in a water-channel simulation. Plume concentration statistics extracted from the physical modelling in the wind-tunnel and water-channel simulations are compared to those obtained from a field experiment. The modification of the detailed structure of the plume as it interacts with the obstacles is investigated. To this purpose, measurements of the evolution of the mean concentration, concentration fluctuation intensity, concentration probability density function, and integral time scale of concentration fluctuations in the array plume obtained from the field experiment and the scaled wind-tunnel and water-channel experiments are reported and compared, as well as measurements of upwind and within-array velocity spectra. Generally, the wind-tunnel and water-channel results on the modification of the detailed plume structure by the obstacles were qualitatively similar to those observed in the field experiments. However, with the appropriate scaling, the water-channel simulations were able to reproduce quantitatively the results of the full-scale field experiments better than the wind-tunnel simulations.  相似文献   

偏流角对星载三线阵相机摄影的影响   总被引：1，自引：0，他引：1  

胡燕  胡莘  王新义  赵斐 《测绘科学》2006,31(4):62-63

本文通过介绍偏流角的产生原因以及星载三线阵CCD相机的成像特点,结合具体算例分析了偏流角以及剩余偏流角对星载三线阵相机摄影的影响,提出为了保证三线阵影像的有效立体重叠,必须对偏流角进行修正。  相似文献   

从阵列声波测井波形处理地层纵、横波时差的新方法   总被引：4，自引：5，他引：4  

朱留方  沈建国 《地球物理学进展》2006,21(2):483-488

阵列声波测井波形中包含丰富的地层纵、横波速度信息.如何从这些波形中提取出这些速度信息,得到比较准确的地层纵、横波时差是资料应用人员非常关心的问题.目前,最常用的纵、横时差处理方法是STC———慢度—时间相关法.该方法只有在波形的速度频散不严重时比较有效.而井内声波传播的基本特征是具有频散特征.利用Ma-trix pencil方法可以求出阵列声波测井波形的二维谱.借助于波形的二维谱,本文给出一种求地层的纵、横波时差的方法.本方法充分利用井内声波传播的规律,有效地减小了频散对纵、横波时差计算的影响,得到的纵、横波时差值精度比较高.  相似文献   

上海地震台阵标定结果研究     

于海英  朱元清  阚道玲  赵书礼 《中国地震》2006,22(2):190-196

本文阐述了地震台阵标定理论和上海地震台阵的标定方法，并对上海台阵标定结果进行了分析：给出2个典型地震的台阵标定结果；对日本北海道地区和本州地区的地震标定差别进行了研究；研究了不同方向、不同震中距和不同震级的地震标定结果。讨论结果表明，上海地震台阵标定显著提高了定位的精度。  相似文献   

地震台阵上信号方位角和慢度的时、频域估计方法比较   总被引：2，自引：0，他引：2       下载免费PDF全文

严锋  靳平  范广超 《地震工程学报》2006,28(4):327-330

地震台阵常用频率-波数分析法来估计地震信号的后方位角和慢度。尽管有关的算法是众所周知的,但不同的实现在某些情况下可能导致不同的结果。如应用在宽频带的澳大利亚WRA台阵的记录时,标准的f-k分析方法往往给出不正确的结果。本文发现错误是由FFT的频谱泄漏效应引起的,如在进行FFT之前对原始数据进行高通滤波则可以有效地避免这样的错误。进一步对在时域中直接估算信号方位角和慢度的一种算法进行了分析,比较发现时域方法的计算速度和精度都不低于频域方法,且在某些低信噪比的情况下,前者可以给出更可靠的结果。  相似文献