海域和陆域地震动输入能量与强度指标相关性

Correlation between input energy and intensity measures of offshore and onshore ground motions

摘要:

为给概率地震危险性分析提供依据,研究了海域和陆域地震动弹性输入能量与其他地震动强度指标的相关性及海陆差异。基于日本K-NET台网的271次地震事件,包含1 784条海域地震动记录和4 480条陆域地震动记录,通过相关性分析选取了7个代表性强度指标。首先,计算了不同震中距下强度指标与绝对和相对输入能量的相关性,并从不同周期段及震中距的角度分析了结果；其次,对不同阻尼比下强度指标与绝对和相对输入能量进行相关性分析；最后,对比了海陆强度指标与输入能量的相关性差异。结果表明:在不同周期段,海域和陆域地震动与输入能量相关性最好的强度指标多数相同,但在不同震中距下,强度指标与输入能量相关系数的极值存在海陆差异；在不同阻尼比下,同一强度指标与输入能量的相关性存在海陆差异,初步分析发现该差异可能是海域地震动低频成分丰富造成的。因此在研究输入能量与强度指标相关性时,需考虑阻尼比、震中距的影响。相关结论可为海陆概率地震危险性分析相关研究提供参考。

Abstract:

To provide a basis for probabilistic seismic hazard analysis, this paper investigates the correlation between elastic input energy and other intensity measures of ground motions and the difference between offshore and onshore ground motions. A total of 271 earthquake events were collected from the K-NET of Japan, and 1 784 offshore ground motion records and 4 480 onshore ground motion records were selected. Seven representative intensity measures were determined through correlation analysis. Firstly, the correlation between the selected intensity measures and absolute and relative input energy under different epicentral distances was calculated, and the results were analyzed from the perspectives of period and epicentral distance. Secondly, the correlation between intensity measures and absolute and relative input energy under different damping ratios was analyzed. Finally, the difference in the correlation between offshore and onshore intensity measures and input energy was compared. Results show that the intensity measures that have the best correlation with the input energy of offshore and onshore ground motions are mostly the same in different periods, but there are differences in the extreme values of the correlation coefficient between the intensity measures and the input energy for offshore and onshore ground motions under different epicentral distances. Under different damping ratios, the correlation between the same intensity measures and input energy are different between offshore and onshore ground motions. Through preliminarily analysis, it was found that the difference might be caused by the rich low-frequency components of offshore ground motion. Therefore, the influence of damping ratio and epicenter distance should be considered when studying the correlation between input energy and intensity measures. The results can provide reference for the related research of offshore and onshore probabilistic seismic hazard analysis engineering.