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近年来我国在近断层地震动观测及其对建筑结构地震反应的影响方面开展了有意义的工作,但我国大陆地区获取的近断层脉冲型地震动数量仍非常有限。2014年发生在云南省鲁甸县的Mw6.3级地震造成了与其震级不相称的严重伤亡和建筑震害,除建筑抗震能力和次生灾害等因素之外,破坏力强大的近断层脉冲型地震动也是重要的致灾因素。该文采用基于小波变换的脉冲识别方法,分析了在鲁甸地震中获取的地震动记录的脉冲特性,并与2008年汶川地震中的近断层脉冲型地震动进行了比较。结果显示,与汶川地震中的脉冲型地震动相比,鲁甸龙头记录速度脉冲周期较短,但其速度峰值很大,在6级左右的中等地震中非常少见。此外,该记录的能量分布具有明显的方向性。但由于该台站震中距很小,其成因能否用向前方向性效应解释仍有待商榷。
In recent years, our country has carried out significant work on near-fault ground motion observation and its impact on the seismic response of building structures. However, the number of near-fault impulsive ground motions acquired in China’s mainland is still very limited. The magnitude Mw6.3 earthquake that occurred in Ludian County, Yunnan Province in 2014 caused serious casualties and building damage not commensurate with its magnitude. In addition to factors such as seismic capacity of buildings and secondary disasters, the destructive near-fault impulse type Earthquake is also an important disaster-causing factor. In this paper, a pulse recognition method based on wavelet transform is used to analyze the pulse characteristics of ground motion records obtained from the Ludian earthquake and compared with the near-fault impulsive ground motion in the 2008 Wenchuan earthquake. The results show that compared with the impulsive ground motions in the Wenchuan earthquake, the velocities of the Ludian faucet recording pulses are short, but their peak velocities are very high. It is very rare in moderate earthquakes of magnitude 6 or so. In addition, the recorded energy distribution has a clear directionality. However, due to the epicentral distance of this station is small, its cause can be explained by the forward directivity effect remains to be discussed.