摘要
设计并构造中硬自由场的离心模型,并以此来模拟人工地震动观测台站,在75个重力加速度环境下,获取4组地表及地下不同深度的模拟地震加速度记录,采用考虑相消干涉的传统谱比法,较系统地开展了场地土层地震动效应研究,分析中硬自由场地震反应的振型特征,初步揭示地震动场地放大效应随深度的变化规律。结果表明:在所有振型中,一阶振型在场地放大作用中往往最为显著且容易识别,但并非是所有振型放大系数的最大值,特殊情况下会小于其他振型的放大系数,总体上随深度的增加而增大;对于二阶及高阶振型的地震动放大系数,在土层中部略小于地表和基底处,地表处最大地震动的放大系数出现在15~18 Hz的高频段上;高阶振型与一阶振型对应的频率之比小于理论估算值,且振型越高,差异越大。
The centrifugal model of the medium-hard free field was designed and constructed to be the artificial ground motion observation station. Four group of simulated seismic acceleration records at different depths underground including surface were obtained with gravitational acceleration of 75 g. Nonlinear ground motion effect of soil layer is studied by using the traditional spectral ratio method considering destructive interference,and the vibration mode characteristics of medium-hard free fields ground motion response is analyzed in order to reveals the variation law of the ground motion site amplification effect with depth initially. The results show that the first mode is often the most significant and easy to identify in the field amplification among all modes,but it is not the maximum of all mode amplification factors. In special cases,amplification factor of the first mode is smaller than the other modes. In general,the amplification factor increases with depth. For the second mode and higher modes,the ground motion amplification factor inner of the soil layer is slightly smaller than the surface and base of the soil layer. The amplification factor of the maximum ground motion at the surface appears at 15 Hz–18 Hz which is in the high frequency band. The ratio of the frequency between the higher mode and the first mode is smaller than the theoretical estimation result,the difference will be increased more with the higher modes.
作者
兰景岩
宋锡俊
刘娟
王延伟
LAN Jingyan;SONG Xijun;LIU Juan;WANG Yanwei(Guangxi Key Laboratory of Geomechanics and Geotechnical Engineering,Guilin University of Technology,Guilin,Guangxi 541004,China;Institute of Engineering Mechanics,China Earthquake Administration,Harbin,Heilongiang 150080,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第S02期3696-3705,共10页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51408559)
广西自然科学基金资助项目(2018GXNSFAA281183)
桂林理工大学博士启动基金(GUTQDJJ2016025)。
关键词
土力学
动态离心模型试验
中硬自由场
传统谱比法
场地反应
放大效应
soil mechanics
dynamic centrifugal model test
medium-hard free field
traditional spectral ratio method
ground motion response
amplification effect
