新疆喀什原场地地震动频谱特性研究

Spectral characteristics of ground motions in the original sites of Kashi, Xinjiang

摘要:

2020年1月19日和2020年2月21日在新疆喀什地区先后发生M_S6.4和M_S5.1地震,针对新疆强震动台网收集到的128条强震动记录进行统计分析,研究2次地震记录的幅值及反应谱特性,并与两个现行规范设计反应谱进行对比,结果表明:(1)震级相同时,震中距越小加速度反应谱越大,且加速度反应谱衰减速度越慢;震中距相同时,震级越大加速度反应谱越大,且加速度反应谱衰减速度越慢;(2)震级越大加速度谱值、速度谱值、位移谱值越大;(3)M_S6.4、M_S5.1地震波加速度反应谱及其平均值曲线相近,与我国现行规范加速度反应谱相比差别很大。建议在新疆喀什地区采用基于当地强震记录的加速度反应谱进行结构抗震设计。

Abstract:

Two M_S6.4 and M_S5.1 successive earthquakes occurred in Kashgar, Xinjiang, on January 19, 2020, and February 21, 2020. Based on the statistical analysis of 128 strong ground-motion data records collected by the Xinjiang strong ground-motion data network, the amplitudes and spectral response characteristics of the two earthquakes were investigated. Then, the obtained results were compared with the spectral responses of two current codes. The results show the following: (1) For the same earthquake magnitude, the spectral acceleration response increases and its attenuation speed decreases as the epicentral distance decreases; for the same epicentral distance, the spectral acceleration response increases and its attenuation speed decreases as the earthquake magnitude increases. (2) When the earthquake magnitude increases, the spectral acceleration, spectral ground velocity, and spectral ground displacement increase. (3) The spectral acceleration responses and their average curves of the M_S6.4 and M_S5.1 earthquakes are similar; however, they are quite different from the spectral acceleration responses of the current codes in China. It is recommended that the spectral acceleration response based on local strong earthquake data records should be used in the seismic design of structures in Kashi, Xinjiang.