采用汶川地震强余震26个强震动台站记录，基于H/V谱比法，计算台站场地的强、弱震作用下场地卓越频率之比Rfp和体现强、弱震作用下场地H/V谱比曲线差异程度的DNL，进而识别并分析场地非线性反应特征。结果显示，Rfp、DNL与PGA之间存在显著相关性；其中10个台站出现明显的场地非线性反应特征；大部分台站发生场地非线性反应的PGA阈值为100 cm/s2，部分为50 cm/s2；实例证明，因某些台站不易通过H/V谱比法识别场地卓越频率，因此采用Rfp识别场地非线性反应具有一定局限性。
There are so far not any studies systematically focusing on the nonlinear site response for the strong aftershocks of Wenchuan earthquake. The site responses of the 26 strong-motion stations were estimated using their 1539 recordings collected in the Wenchuan earthquake sequence based on the horizontal-to-vertical spectral ratio (HVSR) method. The nonlinear site response was identified by the two indicators, Rfp (the ratio of the predominant frequency of the site response between the strong and weak ground motion), and DNL (the difference degree of HVSR curves which are calculated with strong and weak ground motion data). The both indicators have significant correlations to the peak ground acceleration (PGA). Obvious evidences were found for 10 strong-motion station to show nonlinear site response. It shows that PGA>100 cm/s2 may be a threshold for ground motions generating a shift of the site response from linearity to nonlinearity. The indicator, Rfp, has some limitations to indentify the nonlinear site response in some cases that the site predominant frequency is difficult to be clearly identified.
2017,38(2): 104-111 收稿日期：2016-12-07
DOI：10.3969/j.issn.1003-3246.2017.02.019
基金项目：中国地震局工程力学研究所基本科研业务费专项（项目编号：2016A04）；地震行业科研专项经费项目（项目编号：201508005）；国家自然科学基金（项目编号：U1534202）；中国地震局创新团队发展计划
作者简介：姚鑫鑫(1994-),女,硕士研究生,主要从事工程地震研究。E-mail:yaoxinxiniem@126.com
*通讯作者：任叶飞(1983-),男,副研究员,主要从事工程地震相关研究。E-mail:renyefei@iem.net.cn
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