土-结构相互作用对地震动记录的影响——以通信塔为例

Effects of soil-structure interaction on ground motion records: A case study of the communication tower

为提高地震监测密度,近年来我国在非自由场布设了较多的地震烈度仪用于烈度速报,部分布设在通信公司的通信塔附近,站址附近结构物对地震动记录有一定影响。本文以通信塔为例,研究了土-结构相互作用对地震动记录的影响。在建立土-通信塔耦合单自由度体系,分析土层和结构动力参数对地震动记录的影响规律的基础上,利用ABAQUS有限元软件建立自由场和土-通信塔的三维有限元模型,计算分析了不同工况下土-通信塔相互作用对基础地震动加速度峰值和频谱的影响。结果表明:(1)土-通信塔相互作用对基础处地震动加速度峰值影响较小,但对某些频段的频谱影响较大;(2)土-通信塔相互作用对地震动加速度峰值和频谱的影响随着到基础中心距离的增加减小显著;(3)在通信塔附近布设台站时,本文建议布设在距离通信塔0.2H以外,以减小土-通信塔相互作用对台站地震动记录的影响。

To improve the network density of earthquake monitoring,China has set up many seismic intensity meters in the non-free field for seismic intensity rapid reporting in recent years.Part of seismic intensity meters are mounted near the communication towers of communication company,and the ground motions recorded by the seismic intensity meters are to some extent influenced by the structures nearby.In this paper,the effect of soil-structure interaction on ground motion records are studied,with communication tower as an example.Based on the analysis of the influence characteristics of soil and structural dynamic parameters on ground motion records using simplified single degree of freedom for the soil-communication tower,a 3-D finite element model of free field and soil-communication tower is established using ABAQUS finite element software.The effect of soil-communication tower interaction on the peak ground acceleration and spectrum thereof under different working conditions is analyzed.The results show that:(1)the soil-communication tower interaction has little effect on the peak ground acceleration,but has a relatively larger influence on the spectrum in some frequency bands;(2)the effect of soil-communication tower interaction on the amplitude and spectrum of ground motion acceleration decreases significantly with the increase of the distance from the base center;(3)when the station is installed near the communication tower,this paper proposes to lay out the distance 0.2H,H the height of the tower,away from the communication tower,so as to reduce the effect of soil-communication tower interaction on station ground motion records.