近断层速度大脉冲对反应谱的放大作用

发布时间：2018-11-16 16:04

【摘要】：收集我国近年发生的汶川地震、鲁甸地震和美国NGA(Next Generation Attenuation)数据库选取的175次地震事件3661组强震动记录,考虑脉冲方向的不确定性,基于小波方法定量识别出165条典型速度脉冲记录,利用小波提取出速度脉冲记录中的长周期脉冲信号,通过对比分析原始脉冲记录和提取出长周期脉冲后的残余记录的反应谱特征,研究发现速度大脉冲在其特征周期T_p附近对反应谱有很强的放大作用,这种作用表现为一种窄带效应。基于偏差参数定量揭示了大脉冲在不同周期段对反应谱的放大作用,放大曲线变现为以脉冲特征周期T_p为中心的单峰曲线,在周期T_p处放大倍数最大可达3.5倍,往两侧逐渐变弱,主要影响周期范围为0.5T_p~2T_p。利用最小二乘回归方法分别给出了脉冲放大系数Af和脉冲周期T_p的经验模型,探讨了地震震级、场地剪切波速对放大系数曲线的影响。研究表明:随震级增大,脉冲放大作用影响的周期范围变宽,放大系数曲线的峰值周期向长周期方向移动;随场地剪切波速增大,脉冲放大作用的影响范围和峰值均向短周期移动,相比震级而言,场地剪切波速对放大系数曲线的影响较小。该文脉冲放大作用的经验结果可用于给定地震环境下(如震级、场地剪切波速)近断层场地速度大脉冲作用下对反应谱的修正。
[Abstract]:To collect 3661 sets of strong motion records of the Wenchuan earthquake, the Ludian earthquake and the 175 earthquakes selected from the NGA (Next Generation Attenuation) database of the United States in recent years in China, considering the uncertainty of the direction of the pulse, Based on the wavelet method, 165 typical velocity pulse records are quantitatively identified, and the long-period pulse signals are extracted from the velocity pulse records by wavelet transform. By comparing and analyzing the response spectrum characteristics of the original pulse record and the residual record after extracting the long period pulse, it is found that the large velocity pulse has a strong amplification effect on the response spectrum near the characteristic period T _ p. The effect is a narrow band effect. Based on the deviation parameters, the amplification effect of large pulse on the response spectrum in different periods is quantitatively revealed. The amplification curve is turned into a single-peak curve centered on the pulse characteristic period T _ p, and the maximum amplification multiple can be up to 3.5 times at periodic T _ p. On both sides, the main influence period is 0.5T / s, 2T / s. The empirical models of pulse magnification factor (Af) and pulse period (T _ p) are given by using the least square regression method. The effects of magnitude and site shear wave velocity on the magnification factor curve are discussed. The results show that with the increase of magnitude, the period range of the effect of pulse amplification becomes wider, and the peak period of magnification factor curve moves to the direction of long period. With the increase of site shear wave velocity, the influence range and peak value of pulse amplification move to short period, compared with magnitude, the influence of site shear wave velocity on magnification coefficient curve is less. The empirical results of pulse amplification can be used to modify the response spectrum in a given earthquake environment (such as magnitude, site shear wave velocity) near the fault site under the action of large pulse velocity.
【作者单位】：中国地震局地球物理研究所;北京工业大学建筑工程学院;中国地震风险与保险实验室;
【基金】：国家科技支撑计划项目(2012BAK15B01) 国家自然科学基金项目(51208476,51578513,51421005)
【分类号】：P315.9

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