The main ship channel bridge of the Hutong Changjiang River Bridge is a double-py-lon continuous steel truss girder cable-stayed bridge with span arrangement (140+462+1 092+462+140) m .The foundation for the main pier No .29 of the bridge is the rectangular open caisson with rounded corners .To study the mechanical characteristics of the caisson structure and its foun-dation bed after construction of the caisson and the bridge ,the finite element software ABAQUS was used to establish the three-dimensional solid model for the caisson and foundation bed interac-tion and the stress and deformation of the foundation bed and side wall soil of the caisson under 5 load combinations were analyzed .The results of the analysis show that after the construction of the caisson and the bridge ,the differences of the longitudinal and transverse stress distribution of the foundation bed and side wall soil of the caisson are great .The vertical stress of the foundation bed is relatively uniform ,the additional stress of the foundation bed soil corresponding to the par-tition walls of the caisson is slightly great and the additional stress of the side wall soil in the depth range of the caisson is considerably affected by the corresponding positions of the partition walls . The foundation bed soil and the caisson structure have suffered certain settlement deformation ,the settlement differences of the caisson are mainly caused by the erection of the steel truss girder and the settlement has considerable influence on the superstructure of the bridge .%沪通长江大桥主航道桥为(140+462+1 092+462+140 ) m双塔连续钢桁梁斜拉桥 , 29号主墩采用倒圆角的矩形沉井基础.为研究沉井施工及桥梁施工后沉井结构与地基间的受力特性 ,采用ABAQUS有限元软件建立沉井-地基相互作用的三维实体模型 ,分析5种荷载组合下沉井基底和侧壁土体的应力和变形.结果表明 ,沉井施工和桥梁施工后 ,沉井基底和侧壁土体应力沿纵、横向分布差异较大 ;基底的竖向应力相对较为均匀 ,沉井隔墙对应处基底土体的附加应力略大;沉井深度范围内侧壁土体的附加应力受相应隔墙位置的影响显著 ;地基土体和沉井结构产生了一定的沉降变形 ,沉井的沉降差异主要由架梁引起 ,且对桥梁上部结构影响较大.
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