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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。
This paper collects 3661 records of strong earthquakes in 175 earthquakes selected by Wenchuan Earthquake, Ludian Earthquake and NGA (Next Generation Attenuation) database in China in recent years. Taking into account the uncertainty of pulse direction, 165 typical velocities are identified based on the wavelet method Pulse recording, the use of wavelet extraction speed pulse recording long-period pulse signal, by comparing the original pulse recording and extraction of the long-period pulse residual recording response spectrum characteristics of the study found that the speed pulse in its characteristic period T_p near Response spectrum has a strong amplification effect, this effect is manifested as a narrowband effect. Based on the deviation parameters, the amplifying effect of large pulses on the response spectra was revealed quantitatively. The amplification curve was realized as a single-peak curve with the pulse characteristic period T_p as the center. The maximum magnification at the period T_p was up to 3.5 times, Gradually weakened, the main impact of the cycle range of 0.5T_p ~ 2T_p. Empirical mode of pulse amplification factor Af and pulse period T_p are respectively given by least square regression method. The influence of earthquake magnitude and shear wave velocity on amplification coefficient curve is discussed. The results show that as the magnitude increases, the period of pulse amplification effect broadens, and the peak period of the amplification coefficient curve moves to the long period. With the increase of field shear wave velocity, the influence range and peak value of pulse amplification effect are both short period Compared with the magnitude, the effect of site shear wave velocity on the amplification coefficient curve is small. The empirical results of this paper can be used to correct the response spectrum under the influence of the large velocity pulse near the fault in a given earthquake environment (such as magnitude and shear wave velocity).