An Experimental Study on Engineering Characteristics of Spatial Correlation of Earthquake Ground Motion

尽管在工程上具有重要意义，但几百米距离上的地震地面运动的空间相关性还没有得到详细的研究。为了从工程角度对上述特性进行实验检验，在东京大学千叶实验站建立了以下观测系统：1)在地面（-1m和-20m）安装8台3分量加速度型地震仪；先前存在的密集阵列网络已经扩展到一个由44个地震仪组成的系统，在一个边长约300米的三角形区域内，共有132个组件。通过该扩展，可以根据实际观测到的地震记录研究300米、150米、120米、30米、15米、10米和5米距离上地面运动的空间相关特征。2)日本气象厅（JMA）的位移式地震仪（2位）。1个角。分量)和三种速度型地震…与1台井眼加速度型地震仪（2台井眼加速度型地震仪）一起安装了2台井眼加速度型地震仪。1个角。分量)，以检验加速度型地震仪记录积分所得位移时程的可靠性。由于整个观测系统在1985年12月才开始运作，尚未获得完整的、令人满意的记录。然而，通过使用迄今记录的数据，我们发现了一些有趣的现象。(1)在2 ~ 13s周期范围内的地震波分量上，加速度型地震仪和速度型地震仪记录的地震波分量的一致性令人满意，至少在大于45 s周期的地震波分量上，加速度型地震仪和速度型地震仪记录的地震波分量的一致性令人满意。在地质条件基本一致的300m三角形区域内，地表加速度峰值变化系数为20%。这似乎是未来地震动空间相关性研究的一个重要方向。少

In spite of its engineering importance, spatial correlation of earthquake ground motion over a distance of several hundreds of meters has not been studied in detail. In order to experimentally examine the abovementioned properties from the engineering point of view, the following observation system has been constructed in the Chiba Experiment Station of the University of Tokyo.1) By installing eight 3-component acceleration-type seismographs on and in the ground (-1m and -20m, respectively), the previously existing dense array network has been expanded to a system of 44 seismographs with a total number of 132 components within a triangular area with sides of about 300m. By this expansion, spatial correlation characteristics of ground motions over distances of 300m, 150m, 120m, 30m, 15m, 10m and 5m can be investigated based on actually observed seismograms.2) A JMA (Japan Meteorological Agency) displacement-type seismograph (2 horiz. and 1 vert. components) and three velocity-type seism … More ographs(2 horiz. and 1 vert.) with wide dynamic range have been installed together with a borehole acceleration-type seismograph (2 horiz. and 1 vert. components) at the same place to examine the reliability of displacement time-histories obtained by integration of the records of acceleration- type seismograph.Since the total observation system began to operate only in December, 1985, complete sets of satisfactory records are yet to be obtained. However, some interesting findings have been made by using the data so far recorded.1) The displacement waveform computed by double integration of accelero gram was found to agree with that recorded by the JMA displacement-type seismograph for the components of waves in the period range of 2 - 13s.2) Agreement between ground motions recorded by acceleration-type and velocity-type seismographs was found satisfactory at least for the components of waves with periods longer than 4s.3) From the two of the strongest array records so far obtained, the peak acceleration on the ground surface was found to vary with a coefficient of variation of 20% within the 300m triangular area whose geological conditions are almost uniform. This seems to indicate an important direction of future research related to the spatial correlation of ground motion. Less