沿海软土地区浅部土层地震运动特征研究  

Research on seismic motion in shallow depth in coastal soft soil area

作　　者：高彦斌[1] 晁浩 GAO Yanbin;CHAO Hao(College of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程学院,上海200092

出　　处：《地震工程与工程振动》2024年第4期193-200,共8页Earthquake Engineering and Engineering Dynamics

基　　金：国家自然科学基金项目(41972273)。

摘　　要：沿海软土地区的深厚覆盖层会明显放大地震动,对工程建设产生不利影响。基于一维水平土层地震反应的频域分析方法,采用等效线性化动力计算模型,输入不同的地震动,分析7度设防地震下不同场地条件下的浅部场地地震运动特征。研究结果表明:浅部软土厚度以及地震动频谱差异会明显影响浅部土层(70 m以内)的最大加速度、最大剪应力、最大剪应变和相对位移。相对位移随深度的变化规律不符合规范建议的余弦函数的特征,余弦曲线明显低估较浅位置的位移变化率(剪应变),而高估较深位置的位移变化率(剪应变)。提出了一个拟合关系式来预估7度设防地震下沿海软土地区70 m以内浅部土层的相对位移,该拟合关系具有一定的局限性,但可对沿海地区地下工程地震响应分析提供参考。The deep overburden in coastal soft soil areas will magnify ground motion significantly,which will have adverse effects on engineering construction.Based on the frequency domain analysis method of seismic response in one-dimensional horizontal soil layer,inputting different seismic waves,the equivalent linearized dynamic calculation model is used to analyze the shallow site seismic motion characteristics of different site conditions under 7-degree seismic fortification.The calculation results show that the maximum acceleration,the maximum shear stress,the maximum shear strain and relative displacement of the shallow soil layer within 70 m can be significantly affected by the difference of shallow soil layer thickness or seismic wave spectrum.The variation of relative displacement with depth does not conform to the characteristics of cosine function recommended by the code.The cosine curve apparently underestimates the rate of change in displacement(shear strain)at the shallower position and overestimates the rate of change in displacement(shear strain)at the deeper position.In this paper,a fitting relation is proposed to estimate the relative displacement of shallow soil layers within 70 m in coastal soft soil areas under 7-degree seismic fortification.This fitting relation has certain limitations,but can provide reference for seismic response analysis of underground engineering in coastal areas.

关 键 词：软土 地震响应 地下工程 相对位移 

分 类 号：TU435[建筑科学—岩土工程]