北京市区小区域地震影响
MICRO-ZONATION OF SEISMIC EFFECT IN BEIJING CITY
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摘要: 文中研究了北京及其周围地区的历史地震和地震地质资料,并在此基础上估计了基岩运动的参数。众所周知,局部地质、地形和土质条件等许多因素对给定场地的地面运动特性都是有影响的。本文着重考虑了土层的特性对地面运动的影响.作为分析工作的基础,我们研究了北京地区典型土层的动力特性。为了分析市区各场地上的地震反应,我们将它分成面积大体相等的许多网格,对于每一网格都分析了相应土层柱状在指定输入运动下的地震反应,通过电子计算和绘图装置将结果用许多图件表示,从而给出了不同场地上地震反应谱和强震地面运动的地区分布。这些图件可用来作为制定土地利用和防震规划的参考。我们根据市区每一地点的计算反应谱和典型结构的平均周期确定了相应结构的地震系数,结果已绘成等值线,这些图件可作为典型结构的震害预测和抗震设计的参考。Abstract: The historical earthquakes and seismotectonic data of Beijing and surrounding areas are described based on which parameters of input excitations of the basement rocks have been evaluated. It, is known that many factors such as local geology, topography and soil conditions can affect the characteristics of ground motion at a given site. But in this paper, we lay emphasis only upon analyzing the influence of soil layer characteristics on ground motion. As a basis of analysis, some dynamic properties of typical soil in Beijing area have been studied. In order to analyze seismic response of each part of the city, the urban region is divided into many grids of roughly equal areas. For each grid the dynamic analysis of the corresponding soil column under prescribed input movement has been done. The results are represented by a series of maps obtained through a computer controlled plotter. They show the regional distribution of parameters of strong ground motion and earthquake response spectra at different sites. These graphs can be used as a reference in making land-use and anti-seismic planning. Besides, on the basis of calculated response spectrum for each part of the city and the average period of typical structures we determine the effective seismic factor for such structures and plot as contour lines which may be taken into consideration in designing and predicting earthquake hazards for typical structures.
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[1] 李自强,北京的地震,地球物理学报,6, 2, 1957.
[2] I. M.Idriss, H. B. Seed, Sesponse of Horizontal Soil Layers, Journal of the Soil Mechanics and Foundtions Division, Proc. of ASCE 94, SM4, 1003—1031, 1968.
[3] R. V, Whitman, etc., Accuracy of Model Superposition of One—Dimensional Soil Amplicatiun Analysis, Proc. Int. Conf. On Microzonation, Seattle, 1, 483—497, 1972.
[4] H. B. Seed, I. M. Idriss and F. W. Kieter, Characteristics of Rock Motions During Earthquakes, Report EERC, Berkeley, University of California, 1968.
[5] 陈达生等,抗震建筑的设计反应谱、中国科学院工程力学研究所地震工程研究报告集,第三集,科学出版社,1977.
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