摘要
通过克拉玛依、浙江46个场地的地脉动单点三分向记录和两次地震的强震记录,对比了戈壁荒漠地区地脉动与地震动的H/V谱比,分析了地脉动H/V谱比卓越频率与覆盖层厚度、不同深度等效剪切波速以及特征周期之间的相关性,研究了基于地脉动单点谱比的场地特征参数测定方法在戈壁荒漠等覆盖层较薄以及东部沿海等覆盖层较厚地区的适用性,对该方法的高频、低频部分进行修正,扩展了适用频带范围。结果表明,在戈壁砂砾地区,地震动与地脉动H/V谱比的卓越频率具有很高的一致性;基于地脉动单点谱比的场地特征参数测定方法在计算场地覆盖层厚度、覆盖层等效周期时,对于东部沿海等深厚覆盖层场地会低估,对于戈壁荒漠等浅覆盖层场地会高估;对该方法修正后,适用频带范围扩展到了0.58~12.5 Hz,计算的场地覆盖层厚度、覆盖层等效周期与实测值的平均相对误差提高到了22%和27%;在0.58~12.5 Hz频带,场地V s20、V s30、T s20、T s30、T s与地脉动卓越频率也体现出了明显的相关性,V s30,T s30与地脉动卓越频率的相关性要大于V s20,T s20。
Combining the 46 microtremor single 3-components records of Karamay and Zhejiang with records of two earthquakes,the H/V spectral ratio of microtremor and earthquake motion in the desert region was compared.The correlation between the predominant frequency of microtremor and the equivalent shear wave velocity at different depth of overburden and the characteristic period was analyzed.The applicability of the method was studied to determine the site characteristic parameters based on the single point spectral ratio of microtremor in areas with thinner overburden in desert and thicker overburden in eastern coastal areas.The results show that in the desert region,the predominant frequency of H/V spectral curve of ground motion and microtremor has high consistency.The method that determined the site characteristic parameters based on the single point spectral ratio of microtremor was used to calculate the thickness of sediments and site period.It was shown that deep overburden sites such as the eastern coast was underestimated and shallow overburden sites such as the desert was overestimated.The method was modified with the results of 46 microtremor tests,and the fitting relationship between the predominant frequency and the site characteristic parameters with the interval distribution of 0.58-12.5 Hz in frequency domain were obtained.In this range,V s20,V s30,T s20,T s30 has a significant correlation with predominant frequency of microtremor.The correlation between V s30,T s30 and the predominant frequency of microtremor is bigger than that between V s20,T s20 and the predominant frequency.
作者
师黎静
陈盛扬
SHI Lijing;CHEN Shengyang(Key Laboratory of Earthquake Engineering&Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China;Department of Structural Engineering,Tongji University,Shanghai 200092,China)
出处
《振动与冲击》
EI
CSCD
北大核心
2020年第11期138-145,共8页
Journal of Vibration and Shock
基金
国家重点研发计划(2018YFC1504601
2018YFC1504004)
中国地震局工程力学研究所基本科研业务专项资金项目(2016A04
2014B06)。
关键词
地脉动
卓越频率
覆盖层厚度
等效剪切波速
特征周期
microtremor
predominant frequency
thickness of sediments
equivalent shear wave velocity
site period
