利用强震动记录的谱比分析场地非线性反应
发布时间：2018-09-06 14:56
【摘要】：场地效应直接影响地震灾害的严重程度,一直以来都是地震工程领域的研究热点。场地非线性反应作为场地效应之一,也备受国内外学者的关注。大量研究结果表明,土体在强地震动作用下的应变幅值增加,剪切模量随之降低而阻尼比增强,引起场地卓越频率向低频段移动,场地放大在长周期段显著提升。因此,研究场地发生非线性反应现象对于工程结构选址、抗震理论的完善,尤其是规范设计反应谱的标定是必须考虑的关键问题。同时研究场地非线性反应的特征以及产生非线性的地震动阈值至关重要。我国数字强震动观测台网在2007年至2013年期间捕获了大量高质量的主余震加速度记录,为研究场地非线性提供了良好的契机。本文以上述理论和数据资料为基础,对我国强震动台站场地非线性反应展开研究,完成的主要工作与取得的结论如下:1、按照一定原则筛选出50个台站的强震动观测记录,并对所有选取记录进行数据处理,基于傅里叶振幅H/V谱比法,将记录按照PGA值分档类计算傅氏谱比平均值曲线并识别卓越频率。结果表明,通过对比各档类HVSR曲线对应的卓越频率可以初步判断出台站场地是否发生非线性反应,谱比法对于非线性识别具有良好的适用性和可靠性。2、研究50个台站场地非线性反应四种参数(Rfp、DNL、ADNL、PNL)与地面加速度峰值(PGA)的对应关系及其相关性,并选用相应的值判断发生场地非线性反应的台站,确定发生场地非线性反应的参数阈值。结果显示,对于大部分台站四个参数规律均体现了强震动作用下场地非线性反应的显著特征,并识别出24个台站发生了场地非线性反应。本文建议发生场地非线性反应的PGA阈值为100gal,ADNL阈值为0.2,PNL阈值为0.2,Rfp的阈值为0.75。3、利用台站捕获的不同时间段地震记录和2007年、2009年台站地脉动数据,结合台站场地条件等因素,分析记录不同时间段非线性反应参数变化规律,以及识别到的弱震记录卓越频率变化趋势,结果表明,中硬场地土或者弱震作用下的台站场地对应了线性地震响应或发生了短暂的非线性反应行为,卓越频率在短周期内即可恢复。中软场地土或者强震动作用下的台站场地则对应非线性地震响应,卓越频率通常以1年为恢复周期。
[Abstract]:Site effect, which directly affects the severity of earthquake disaster, has always been a hot topic in the field of seismic engineering. As one of the site effects, the site nonlinear response has also attracted the attention of scholars at home and abroad. A large number of results show that the shear modulus decreases and the damping ratio increases with the increase of the strain amplitude of the soil under strong ground motion, which causes the excellent frequency of the site to move to the low frequency band and the amplification of the site to increase significantly in the long period. Therefore, the study of nonlinear site response is a key problem to be considered for site selection, seismic theory improvement, especially the calibration of the response spectrum of the code design. At the same time, it is very important to study the characteristics of site nonlinear response and to produce nonlinear threshold of ground motion. The digital strong motion observation network in China captured a large number of high quality aftershock acceleration records from 2007 to 2013, which provides a good opportunity for the study of site nonlinearity. Based on the above theory and data, the nonlinear response of strong motion stations in China is studied in this paper. The main work and conclusions are as follows: 1. According to certain principles, 50 observational records of strong motion are selected. Based on the Fourier amplitude H / V spectral ratio method, the average value curve of the Fourier spectrum ratio is calculated according to the class of PGA value and the excellent frequency is recognized. The results show that the nonlinear response of the station site can be preliminarily determined by comparing the superior frequency corresponding to the HVSR curves of each class. The spectral ratio method has good applicability and reliability for nonlinear identification. The relationship between the four parameters (Rfp,DNL,ADNL,PNL) of nonlinear response of 50 stations and the peak (PGA) of ground acceleration and its correlation are studied. At the same time, the corresponding values are selected to judge the station where the site nonlinear reaction occurs, and the parameter threshold of the site nonlinear reaction is determined. The results show that for most of the stations, the four parameter laws reflect the obvious characteristics of the site nonlinear response under strong vibration, and 24 stations have been identified to have the site nonlinear response. In this paper, we suggest that the threshold value of PGA for site nonlinear response is 0.2g / a, and the threshold is 0.75.3.Using the seismic records of different time periods captured by the station and the seismic pulsation data of the stations in 2007 and 2009, combining with the station site conditions and so on, The variation of nonlinear response parameters in different time periods is analyzed, and the dominant frequency variation trend of weak seismic records is identified. The results show that, The intermediate hard soil or the station site under the action of weak earthquake corresponds to the linear seismic response or the transient nonlinear response behavior, and the excellent frequency can be recovered in a short period. The seismic response of the medium soft soil or the station site under strong vibration is corresponding to nonlinear seismic response, and the excellent frequency usually takes one year as the recovery period.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.9
[Abstract]:Site effect, which directly affects the severity of earthquake disaster, has always been a hot topic in the field of seismic engineering. As one of the site effects, the site nonlinear response has also attracted the attention of scholars at home and abroad. A large number of results show that the shear modulus decreases and the damping ratio increases with the increase of the strain amplitude of the soil under strong ground motion, which causes the excellent frequency of the site to move to the low frequency band and the amplification of the site to increase significantly in the long period. Therefore, the study of nonlinear site response is a key problem to be considered for site selection, seismic theory improvement, especially the calibration of the response spectrum of the code design. At the same time, it is very important to study the characteristics of site nonlinear response and to produce nonlinear threshold of ground motion. The digital strong motion observation network in China captured a large number of high quality aftershock acceleration records from 2007 to 2013, which provides a good opportunity for the study of site nonlinearity. Based on the above theory and data, the nonlinear response of strong motion stations in China is studied in this paper. The main work and conclusions are as follows: 1. According to certain principles, 50 observational records of strong motion are selected. Based on the Fourier amplitude H / V spectral ratio method, the average value curve of the Fourier spectrum ratio is calculated according to the class of PGA value and the excellent frequency is recognized. The results show that the nonlinear response of the station site can be preliminarily determined by comparing the superior frequency corresponding to the HVSR curves of each class. The spectral ratio method has good applicability and reliability for nonlinear identification. The relationship between the four parameters (Rfp,DNL,ADNL,PNL) of nonlinear response of 50 stations and the peak (PGA) of ground acceleration and its correlation are studied. At the same time, the corresponding values are selected to judge the station where the site nonlinear reaction occurs, and the parameter threshold of the site nonlinear reaction is determined. The results show that for most of the stations, the four parameter laws reflect the obvious characteristics of the site nonlinear response under strong vibration, and 24 stations have been identified to have the site nonlinear response. In this paper, we suggest that the threshold value of PGA for site nonlinear response is 0.2g / a, and the threshold is 0.75.3.Using the seismic records of different time periods captured by the station and the seismic pulsation data of the stations in 2007 and 2009, combining with the station site conditions and so on, The variation of nonlinear response parameters in different time periods is analyzed, and the dominant frequency variation trend of weak seismic records is identified. The results show that, The intermediate hard soil or the station site under the action of weak earthquake corresponds to the linear seismic response or the transient nonlinear response behavior, and the excellent frequency can be recovered in a short period. The seismic response of the medium soft soil or the station site under strong vibration is corresponding to nonlinear seismic response, and the excellent frequency usually takes one year as the recovery period.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.9
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相关期刊论文 前6条
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5 任叶飞;温瑞智;山中浩明;鹿]嬁∮，
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