2019年6月18日日本山形县Mw6.7级地震场地非线性反应特征研究

Study on Nonlinear Site Response Characteristics of the Yamagata Mw 6.7 Earthquake in Japan on June 18^(th),2019

强震作用下的土层非线性是研究场地效应的重要因素之一。选取2019年6月18日日本山形Mw6.7级地震中8个台站的主震及20次余震的强震动记录,采用主余震速度反应谱水平/垂直(HVSR)谱比,并结合非线性识别指标DNL、ADNL和PNL对主震中可能发生非线性反应特征的台站进行研究。结果表明:土体在强震动作用下场地卓越频率有向低频移动的趋势,体现了土层非线性反应的特征;非线性指标DNL和ADNL与地震动峰值加速度之间存在显著的相关性,但PNL对应关系不明显。

Soil nonlinearity under strong earthquake is one of the important factors for the site response research.This paper selects strong motion records of the mainshock and 20 aftershocks of 8 stations during the Yamagata Mw6.7 earthquake on June 18th,2019,uses the main aftershock velocity response spectrum horizontal/vertical(HVSR)spectrum ratio,and combines the nonlinear identification indexes DNL,ADNL and PNL to study the stations that may have nonlinear response characteristics in the main earthquake.The results show that the predominant frequency of the soil site moves to low frequency under strong vibration,which reflects the characteristics of the nonlinear response of the soil layer;there is a significant correlation between the nonlinear indexes DNL and ADNL and the peak acceleration of ground motion,but the corresponding relationship between PNL is not obvious.