土层不均匀场地对地震反应的影响

工程场地的土层地震反应分析是地震安全性评价的重要组成部分,其结果为抗震设计及震后灾害评估提供主要依据。本文采用库伦-摩尔模型(Mohr-Coulomb)作为土体的本构模型,以粘弹性边界作为截取土层截面后的人工边界条件,使用Abaqus有限元分析软件对安评报告中的场地进行了二维有限元建模,以springs/dashpots单元模拟粘弹性边界,对场地进行有限元分析,研究土层横向不均匀对土层地震反应结构的影响,并且输入实际地震动,分析场地在真实地震下的响应。结果表明:随着土层介质分界面角度的增加,PGA呈规律变化;当分界面角度大于10°时,其PGA放大系数及加速度反应谱和一维水平成层模型有明显差异。

INFLUENCE OF NON-UNIFORM SOIL SITE ON SEISMIC RESPONSE

The seismic response analysis of the soil in the engineering site is an important part of the seismic safety evaluation,and its results provide the main basis for the seismic design and the post-earth-quake disaster assessment.In this paper,the Coulomb-Mohr model is used as the constitutive model of the soil,and the viscoelastic boundary is used as the artificial boundary condition after intercepting the soil section.The two-dimensional finite element model of safety evaluation report was performed Using the ABAQUS finite element analysis software,the springs/dashpots was used to simulate the viscoelastic elastic boundary.The finite element analysis of the site is carried out to study the influence of terrain and soil lateral unevenness on the seismic response structure of the soil,and the actual ground motion is input to analyze the response of the site under real earthquake.The PGA magnification coefficient,the acceleration response spectrum and the one-dimensional horizontal stratification model are significantly different when the interface angle is greater than 10 degrees,with the increase of the angle of the interface.