地震动盆地放大效应与盆地深度关系研究

发布时间：2018-04-03 23:31

本文选题：盆地效应　切入点：地震动　出处：《中国地震局地球物理研究所》2015年硕士论文

【摘要】：我国有许多大中城市位于盆地环境之中,伴随着我国城市现代化建设的快速发展,城市中出现了越来越多的中高层建筑、大跨度城市立交桥等自振周期较长的工程结构。国内外多次大地震的震害调查结果和强震观测均表明：盆地会显著地放大长周期地震动,增加地震动持时,对自振周期较长的工程结构造成比较严重的破坏。然而我国现行的建筑抗震设计规范和地震动预测方程还没有针对地震动盆地放大效应做出特别的考虑,这无疑降低了盆地内建筑物的抗震设防标准。盆地效应涉及的影响因素是很多很复杂的,针对地震动盆地放大效应与盆地深度之间的相关性,本文主要完成了以下几个方面的工作：1.总结现有盆地效应研究进展和方法,将我国学者提出并完善的结合透射边界的解耦的近场波动有限元数值模拟方法用于地震动盆地放大效应研究,直接在盆地底部输入地震动,实现了直接从盆地本身出发刻画地震动盆地放大效应的研究思路。2.作为尝试性的定性研究,分析了小“方形”,“倒凸形”和“曲边形”理想盆地模型的地震动响应特点,揭示了地震动盆地放大效应与盆地深度之间较好的相关性,这与现有一些研究成果的结论是一致的。3.为了更直接地服务于抗震设计规范的修编工作,本研究将盆地浅表的软弱土层剥离掉,不考虑盆地浅表的场地效应,重点研究由于盆地的存在导致的盆地内外软硬基岩之间的地震动放大效应,定义盆地放大系数为盆地内场点地震动加速度反应谱一定周期值与盆地外场点地震动加速度反应谱对应周期值的比值。建立三类理想二维盆地模型,输入台北盆地和渭河盆地周围基岩台站所获得的实际地震记录,研究了实际地震记录作用下盆地对地震动加速度反应谱的放大系数,对大量的计算结果进行了简单的线性和二次曲线拟合分析,得到了初步的加速度反应谱一定周期(1.0s-8.Os)值盆地平均放大系数与盆地深度之间的简单关系。4.研究分析了国内外盆地效应典型的研究成果,重点分析了不同研究所定义的盆地放大系数之间的差异,一定程度上,本文盆地放大系数的含义与利用实际地震记录结合地震动预测方程和实际地震记录标准谱比法得到的盆地放大系数是一致的。最后搜集了“南北地震带”范围内5个盆地的现有数据资料,给出了这5个实际盆地加速度反应谱1.0s周期值盆地放大系数分布图,为这些盆地城市未来的防震减灾规划中考虑盆地效应,提供了一定的参考。
[Abstract]:There are many large and medium-sized cities in China in the basin environment. With the rapid development of urban modernization in China, more and more medium-high-rise buildings and long-span urban flyovers and other engineering structures with long natural vibration period have appeared in the cities.The results of earthquake damage investigation and strong earthquake observation at home and abroad show that the basin will significantly enlarge the long-period ground motion and cause serious damage to the engineering structure with longer natural vibration period when the earthquake duration is increased.However, the current building seismic design code and earthquake prediction equation in China have not made special consideration for the amplification effect of seismic basin, which undoubtedly reduces the seismic fortification standard of buildings in the basin.The influence factors involved in the basin effect are very complicated. In view of the correlation between the amplification effect of the ground motion basin and the depth of the basin, this paper mainly completes the following work: 1.The present research progress and methods of basin effect are summarized. The numerical simulation method of near-field wave coupled with decoupling of transmission boundary proposed by Chinese scholars is used to study the amplification effect of ground motion basin, and the ground motion is input directly at the bottom of the basin.The research idea of describing the amplification effect of ground motion basin directly from the basin itself is realized.As a tentative qualitative study, the characteristics of seismic response of small "square", "inverted convex" and "curved" ideal basin models are analyzed, and the better correlation between the amplification effect and basin depth is revealed.This is consistent with the conclusions of some existing studies.In order to serve the revision of seismic design code more directly, the weak soil layer of the basin is stripped away without considering the site effect of the shallow surface of the basin.Emphasis is placed on the effect of ground motion amplification between soft and hard bedrock in and out of the basin due to the existence of the basin.The magnification factor of the basin is defined as the ratio of the periodic value of the acceleration response spectrum of the point ground motion in the basin to that of the acceleration spectrum of the ground motion at the point of the basin outside the basin.Three kinds of ideal two-dimensional basin models were established to input the actual seismic records obtained from the bedrock stations around the Taibei and Weihe basins. The magnification factor of the acceleration response spectrum of the basin to the ground motion under the action of the actual seismic records was studied.The simple linear and conic fitting analysis of a large number of calculated results is carried out, and the simple relationship between the mean magnification factor and the depth of the basin is obtained from the initial acceleration response spectrum with a certain period of 1.0s-8.Os.The typical research results of basin effect at home and abroad are analyzed, and the differences between basin magnification factors defined by different research institutes are analyzed, to a certain extent,The meaning of the basin magnification factor in this paper is consistent with the basin magnification factor obtained by combining the actual seismic records with the prediction equation of ground motion and the standard spectral ratio method of actual seismic records.Finally, the existing data of five basins in the range of "North and South Seismic Belt" are collected, and the distribution map of magnification factor of these five real basins in the acceleration response spectrum of 1.0s period is given.Some references are provided for the future planning of earthquake prevention and disaster reduction in these basins.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.9

【参考文献】