汶川地震动持时特性分析

发布时间：2018-07-01 18:19

本文选题：地震动持时 + 随机有限断层法　；参考：《南昌航空大学》2017年硕士论文

【摘要】：地震动持时作为地震动三要素之一,已受到地震工程界的广泛关注与深入研究。地震过程中,持时引起的累积破坏效应和低周疲劳现象等对构筑物的损毁造成严重影响,这也已得到业界的普遍认同。持时的重要性由此可见一斑,但其并未如同振幅和频谱被广泛应用到实际工程中。再者,目前持时的计算常根据某一分量的测点记录时程,一个测点将可能得到三个不同大小的持时值,这不便于持时在工程应用上的使用与推广。因此,对持时进行更为深入的分析与研究,将有助于推动持时的理论研究与工程应用。现有的持时研究往往是基于实际地震记录,但台站记录的有限性和震源参数的特殊性等常制约持时影响因素和持时特征的研究。基于此,有必要利用合适的模拟地震动方式,根据现有地震记录反演得到模型参数,合成符合实际地震区域构造环境、地震地质和场地条件的加速度时程,从而对合成时程持时的参数敏感性、空间分布和随断层距的衰减规律等进行分析。本文将基于随机有限断层法,合成符合汶川地震区域特性的加速度时程,进而得到不同持时定义的合成时程持时,以此分析持时的参数敏感性和衰减规律等特征。主要研究内容如下:1)以汶川地震台站记录数据为基础,计算台站记录时程的平面和空间旋转不变平均持时,对比分析两种旋转时程持时与测点记录持时之间的相关性,探讨旋转时程持时的空间分布规律和衰减特性,以论证用旋转时程持时代替测点记录持时的必要性、可行性与合理性。2)采用基于随机有限断层法的EXSIM程序进行地震动加速度时程的合成,并计算不同持时定义方式的合成时程持时,以揭示震级、应力降、kappa值、品质因子和断层上界埋深等参数对合成时程持时的影响规律。3)基于随机有限断层法,参考以往汶川地震震源参数的研究成果,经反演确定汶川地震的震源模型及区域参数,并对合成时程的波形和反应谱进行模拟、从几何衰减和反应谱误差两方面对模型参数的合理性进行检验,然后合成断层距小于300km的87个台站时程,以此分析不同定义的合成时程持时的空间分布规律和随断层距的衰减特性,并与相应测点记录持时进行对比分析。
[Abstract]:As one of the three elements of ground motion, the duration of ground motion has been widely concerned and deeply studied in seismic engineering. During the earthquake, the cumulative damage effect and the low cycle fatigue phenomenon caused by the duration of the earthquake have a serious impact on the damage of the structure, which has been generally accepted by the industry. The importance of time retention can be seen from this, but it is not widely used in practical engineering as amplitude and spectrum. Furthermore, at present, the calculation of time holdup is usually based on the time history of a certain component, and three different durations can be obtained from one measuring point, which is not easy to be used and popularized in engineering applications. Therefore, a more in-depth analysis and research on the timing will be helpful to promote the theoretical research and engineering application. The existing time-lapse studies are often based on the actual seismic records, but the limitation of seismic station records and the particularity of seismic source parameters often restrict the study of the influence factors and characteristics of time-lapse. Based on this, it is necessary to obtain the model parameters according to the existing seismic records by using the suitable simulated ground motion mode, and to synthesize the acceleration time history in accordance with the actual seismic regional tectonic environment, seismic geology and site conditions. The parameter sensitivity, spatial distribution and attenuation law with fault distance are analyzed. Based on the stochastic finite fault method, the acceleration time history which accords with the regional characteristics of Wenchuan earthquake will be synthesized, and then the time holding time of the composite time course with different durations will be obtained, and the characteristics of parameter sensitivity and attenuation law of the time-lapse time will be analyzed. The main contents of this study are as follows: (1) based on the recorded data of Wenchuan earthquake station, the plane and spatial rotation mean duration of station recording time are calculated, and the correlation between the two rotation time duration and the measured point record duration is compared and analyzed. In order to demonstrate the necessity of replacing the holding time of measuring points with the time of rotation, the spatial distribution law and attenuation characteristic of the time of rotation are discussed in order to prove the necessity of replacing the holding time of the measuring point with the time of rotation. Feasibility and reasonableness .2) combining the acceleration time history of ground motion with EXSIM program based on stochastic finite fault method, and calculating the combined time duration of different durations, in order to reveal the magnitude, stress drop and kappa value. Based on stochastic finite fault method and referring to the research results of previous Wenchuan earthquake focal parameters, the source model and regional parameters of Wenchuan earthquake are determined by inversion. The waveform and response spectrum of synthetic time history are simulated, and the rationality of model parameters is tested in terms of geometric attenuation and response spectrum error. Then 87 stations with fault distance less than 300km are synthesized. The spatial distribution law and attenuation characteristics with fault distance of different definitions are analyzed, and the results are compared with those of the corresponding measuring points.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315

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