风尘寺单薄山脊九寨沟余震频谱特征分析

研究近地震场地的地震频谱变化特征,分析其地形效应,能够为边坡支护设计提供依据。通过对九寨沟风尘寺台站实测的3次余震数据对比分析,揭示了不同监测点地震时频谱变化特征。结果表明:相对于山脚监测参考点,山脊监测点FFT主频值较小,集中在7～12 Hz;山脊监测点加速度反应谱特征周期较大,范围为0. 06～0. 12 s; HVSR分析揭示山脊监测点谱比分析的地形放大系数可达12,且存在多个卓越频率,主要在5、30以及50 Hz左右放大较为明显;山脊监测点均方根加速度在水平方向与竖直方向均具有不同程度的放大,且在水平EW向有显著的放大效应,放大系数可达12. 5倍。可见单薄山脊对地震波具有明显的地形放大效应,而且当地震波传播方向与山脊走向大角度相交时地形放大效应最为显著,同时也证实了微地貌对斜坡地震动响应的控制作用。

Analysis of Spectrum Characteristics of Aftershocks in Jiuzhaigou, a Thin Ridge of Fengchen Temple

Studying the spectral variation characteristics of earthquakes near earthquake sites and analyzing their topographic effects can provide a basis for seismic design of high-rise buildings. This paper studies the three aftershocks collected at the monitoring station of Jiuzhaigou Wind Dust Temple, and compares and analyzes the spectrum variation characteristics of different monitoring points. The results show that the peak frequency of the FFT of the mountain monitoring points is smaller than that of the mountain monitoring points. 7-12Hz; the characteristic period of the acceleration response spectrum of the summit monitoring point is large, the range is 0.06-0.12s; the HVSR analysis reveals that the topographic amplification factor of the peak monitoring point spectrum analysis can reach 12, and there are many excellent frequencies, mainly at 5Hz, The amplification of 30Hz and 50Hz is more obvious; the root mean square acceleration of the summit monitoring points has different degrees of amplification in the horizontal direction and the vertical direction, and has a significant amplification effect in the horizontal EW direction, and the amplification factor can reach 12.5 times.