利用F-K谱评价地脉动台阵布设方案

A demonstration of observation array configuration for micro-tremors by F-K spectrum method

为了充分获取有价值的地脉动记录,并兼顾节省观测费用,对常用的台阵进行分析,得到一个布局合理的地脉动台阵布设方案.利用最大似然法,研究圆形、十字形、菱形形状以及测点数量不同的台阵在模拟的正弦衰减波场下所得到的频率波数谱(F-K谱),根据谱极值是否唯一及对应的波数矢量是否与入射波方向一致来评价布设的台阵是否合理,为选择合理的台阵布设方案提供依据.结果表明,菱形台阵布设方案能用较少的测点获得较精确的计算结果,是利用地脉动台阵观测估算场地剪切波速度结构的首选布设方案.

To ensure the rationality of array design and save the cost of observation,the conventional observation array was analyzed,and a rational configuration for micro-tremors was demonstrated in this paper.The frequency-wave number spectrum （F-K spectrum） from records at arrays with different shapes and survey point numbers in a simulated sine decaying wave field was investigated,in which the circle array cross-shaped array and rhombus-shaped array were included.The acceptability of the array configuration was validated by the criterion whether there is one and only one extreme on the F-K spectrum,and whether the direction of the vector is consistent with the direction of the incident wave.The result shows that using the rhombus-shaped array can obtain more precise result with few observation points,and it is the best configuration to estimate the structure of shear wave velocity of site by the micro-tremors array observation method.