缓倾斜液化场地地铁车站结构变形分析

Structure Deformation Analysis of Subway Stations inGently Inclined Liquefaction Sites

为了研究缓倾斜液化场地对地基土-地铁车站结构地震反应的影响,探讨缓倾斜液化场地液化过程中地下结构的位移变形,采用有限差分软件FLAC3D建立缓倾斜液化场地地基土-地铁车站结构的数值分析模型,采用本构模型Finn对所建立的模型进行地震液化分析;通过分析地铁车站结构周围场地液化分布特征、位移云图和地面倾角分别为0°、1°、2°、3°的4种工况下地铁车站的位移时程曲线,探讨地面倾角对周围场地、地铁车站结构的影响,分析4种工况下缓倾斜液化场地中地铁车站结构的位移地震响应。结果表明:在4种工况下,车站周围液化严重,液化分布基本呈对称分布,右侧底部液化程度随地面倾角的增大而增大;车站发生不均匀上浮并且发生逆时针偏转,底板左右两侧最大上浮差值达到6.2 mm;随着地面倾角的增大,土体出现流滑现象,当地面倾角为3°时,土体流滑位移达到1.6 m,并且车站结构发生33 mm的侧向位移;车站层间位移角随着地面倾角的增大而增加,当地面倾角为3°时,层间位移角超过规范限值。

To research influences of gently inclined liquefaction sites on seismic response of foundation soil-subway station structures and explore displacement deformation of underground structures during liquefaction process of gently inclined liquefaction sites,finite difference software FLAC3D was used to establish a numerical analysis model of foundation soil-subway station structure in gently inclined liquefaction sites,and constitutive model Finn was used to carry out seismic liquefaction analysis of the established model.By analyzing liquefaction distribution characteristics of the site around the subway station structure,displacement cloud maps,and displacement time history curves of the subway station under the four working conditions with ground inclination angles of 0°,1°,2°,and 3°,influences of ground inclination angles on surrounding site and subway station structure were discussed,and the displacement seismic response of the subway station structure in gently inclined liquefaction sites under the four working conditions was analyzed.The results show that under the four working conditions,the liquefaction around the station is critical,and the liquefaction distribution is basically symmetrical.The liquefaction degree at the bottom of the right side increases with the increase of the ground inclination angle.Uneven buoyancy and counterclockwise deflection occur in the station,and the maximum buoyancy difference between the left and the right sides of the bottom plate reaches 6.2 mm.With the increase of the ground inclination angle,the soil flow slide phenomenon occurs.When the ground inclination is 3°,the flow slide displacement of the soil reaches 1.6 m,and the station structure has a lateral displacement of 33 mm.The displacement angle between floors increases with the increase of the ground inclination angle.When the ground inclination angle is 3°,the inter-story displacement angle exceeds the specification limit.