Analyses on the effect of the local site conditions on the strong motion based on the array records
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摘要: 基于自贡西山公园山体地形影响台阵和唐山响堂土层场地台阵的地震动记录， 采用互相关分析、 相干系数分析、 傅里叶谱比法和考虑相干系数的傅里叶谱比法， 对比研究了山体地形和土层场地两种局部场地条件对地震动的影响。 结果表明， 局部场地条件下的地震动效应与地震波的频率成分相关。 低频地震波由于其波长较长， 易于穿过土层场地和山体地形发生衍射， 从而导致二者地震动显著相关， 但二者在该频段的地震动场地效应差异不大； 较高频率的地震波由于其波长较短， 更容易受土层场地条件和山体地形条件的影响， 造成二者地震动场地效应差异显著。 此外， 由于山体顶部的尺寸变小， 低频长波长地震波容易在该位置发生衍射， 导致山顶周边测点的地震动相关性增加， 而较高频率的地震波则容易引起山顶局部场地发生共振效应。 山体地形上相邻位置的地震动差异一般较大， 相关性较低， 这与山体地形不同位置的几何形状对较高频率的地震波影响有关； 山底基岩的地震动受山体地形的影响较小， 该位置的地震动效应机制尚需作进一步研究。Abstract: Based on the strong motion records from the topography array of Xishan Park in Zigong and the soil site array of Xiangtang in Tangshan, this paper analyzes the site effects of soil site and hill topography on the ground motion by using the cross-correlation function, coherence function, the Fourier spectral ratio methods with and without consideration of coherence function. The results show that the strong motion effect of the local site conditions is relevant to the frequency content of the input seismic wave. For the low frequency component, its wavelength is so long that it is easy to spread across the soil site and the hill topography, and the diffraction makes the strong motion of the two different local site conditions more related; however, the difference of the site effects in the low frequency band for the two local site conditions is weak. For the seismic wave with high frequency and short wavelength, the strong motion is more likely to be affected by the soil site and the hill topography, therefore the difference of the site effects on the strong motion with high frequency is obvious. In addition, with the decrease of the mountaintop dimension, the diffraction is easy to happen when the seismic wave with low frequency and long wavelength spreads to the mountaintop, leading to increase of the cross-correlation of the ground motions at the observing points surrounding the mountaintop. The resonance effect likely happens when the seismic waves with higher frequency spread to the mountaintop. The strong motion of the adjacent points on the hill topography changes greatly, and their correlation is low, which is caused by the effect of the geometrical shape on the strong motion with higher frequency on the different locations of the hill topography. The strong motion of the bedrock at the bottom of hill is weakly affected by the existence of the hill topography, and its mechanism of the strong motion needs to be further studied.
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本目录中的地震参数来自“中国地震台站观测报告”(简称“月报”)． 其中，国内及邻区给出M≥4.7的事件，全球给出M≥6.0的事件． “月报”由中国地震台网中心按月做出．
本目录中的发震时刻采用协调世界时(UTC)； 为了方便中国读者，也给出北京时(BTC)． 震中位置除给出经纬度外，还给出参考地区名，它仅用作查阅参考，不包含任何政治意义； 还给出测定震源位置的台数(n)和标准偏差(SD)．
面波震级MS是用中周期宽频带SK地震仪记录，采用北京台1965年面波震级公式MS=lg(AH/T)+1.66 lg(Δ)+3.5(1°＜Δ＜130°)求得，AH是两水平分向最大面波位移的矢量合成位移． MS7是对763长周期地震仪记录，采用国际上推荐的面波震级公式MS7=lg(AV/T)+1.66 lg(Δ)+3.3(20°＜Δ＜160°)求得，AV是垂直向面波最大地动位移． mb是短周期体波震级，ML是近震震级. 为避免混乱，震级之间一律不换算．
表 1 中国及邻区地震目录(2015年11—12月， M≥4.7Table 1. Catalog of earthquakes within and near China (November December， 2015, M≥4.7编 号 发震时刻 地理坐标 深度/km 震级 标准偏差(SD) 使用台数(n) 地区 UTC BTC日 时 纬度/°N 经度/°E MS MS7 ML mb 月 日 时:分:秒 1 11 0 21:09:39.8 02 05 22.75 121.70 10 5.6 5.4 5.5 5.1 1.4 101 台湾地区 2 03 00:06:30.7 03 08 24.95 121.95 10 5.2 5.0 5.2 4.5 1.9 90 台湾岛 3 11 15:33:19.3 11 23 24.55 122.70 90 4.4 4.0 4.8 1.9 98 台湾地区 4 13 20:51:34.0 14.04 31.05 128.75 10 7.5 7.3 7.2 2.7 94 中国东海 5 13 21:19:25.9 14 05 30.83 128.72 14 4.8 4.8 2.3 38 中国东海 6 14 19:20:19.0 15 03 31.40 128.80 20 6.2 6.0 5.8 5.6 1.5 102 中国东海 7 14 20:34:27.5 15 04 31.22 128.72 10 5.3 5.0 5.4 4.7 1.5 89 中国东海 8 18 04:38:48:.9 18 12 31.21 128.81 13 5.2 4.8 4.9 4.7 2.3 83 中国东海 9 18 12:18:05.0 18 20 31.00 128.50 10 4.7 4.5 4.3 2.9 44 中国东海 10 19 14:41:50.0 19 22 31.30 128.90 28 4.7 4.4 4.7 4.3 2.7 60 中国东海 11 22 21:02:41.4 23 05 38.01 100.39 10 5.3 5.2 5.0 4.8 2.5 87 青海省 12 25 05:02:02.2 25 13 29.71 90.02 38 4.8 4.6 1.9 27 西藏自治区 -
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图 1 自贡地形台阵测点位置示意图(王伟等，2015)
Figure 1. Location schematic diagram of observation points in the Zigong topography array(after Wang et al, 2015)
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图 2 响堂土层场地台阵测点分布剖面图(卢滔等， 2006)
Figure 2. Distribution of monitoring points in the Xiangtang soil site array (after Lu et al, 2006)
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图 3 自贡地形台阵1—7号测点EW向加速度互相关系数r0-1表示0号与1号测点的互相关系数， 以此类推， 下同
Figure 3. Cross-correlation coefficients of the EW accelerations for the observation points Nos.1-7 of the Zigong topography array r0-1 is the cross-correlation coefficient between the observation points No.0 and No.1, and so on, the same below
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图 4 自贡地形台阵0号测点与其它测点的地震动加速度互相关系数
Figure 4. Cross-correlation coefficients of strong motion acceleration between the observation point No.0 and the others in the Zigong topography array
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图 5 自贡地形台阵1号测点与其它测点的地震动加速度互相关系数
Figure 5. Cross-correlation coefficients of strong motion acceleration between the observation point No.1 and the others in the Zigong topography array
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图 6 自贡地形台阵测点EW向加速度相干系数
Figure 6. Coherence coefficients of the EW acceleration for the observation points in the Zigong topography array
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图 7 自贡地形台阵山顶测点傅里叶谱幅值比
Figure 7. Fourier spectral ratio of the observation points at the top of Zigong topography array
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图 8 自贡地形台阵0号测点与其它测点的EW向加速度相干系数
Figure 8. Coherence coefficients of the EW acceleration between the observation point No.1 and the others in the Zigong topography array
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图 9 响堂土层场地台阵测点的加速度傅里叶谱幅值比
Figure 9. Fourier spectral amplitude ratio of the acceleration for the observation points in the Xiangtang soil site array
表 1 响堂土层场地台阵中1号和2号测井的场地条件
Table 1 Site conditions of the boreholes No.1 and No.2 in Xiangtang soil site array
层号 岩性 层厚/m 层底深度/m 波速/(m·s-1) 1 粉质黏土 4.78 4.78 249 2 细砂 2.45 7.23 270 3 粉土 0.85 8.08 249 4 黏土 4.19 12.27 249 5 强风化黑云变粒岩 6.02 18.29 538 6 强风化花岗质混合岩 13.62 31.91 552 7 中风化花岗质混合岩 0.40 32.31 552 
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期刊类型引用(2)
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2. 黄辅琼, 陈宏峰, 马鸣宇, 马玉川. 2017年9月3日朝鲜核试引起中国东北地区的承压井水位变化初步报道. 国际地震动态. 2018(04): 25-30 . 百度学术
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