桥梁承台基坑开挖对临近桥梁结构影响研究

Study on Influence of Foundation Pit Excavation of Bridge Base Slab on Adjacent Bridge Structures

近年来为解决城市交通拥堵问题,城市高架快速路网建设发展迅速同时桥梁近接施工工程日益增多,基坑开挖对临近既有桥梁的影响成为基坑施工关注的重要问题。利用ABAQUS有限元分析软件结合某新建桥梁上跨轨道交通桥梁工程案例,建立了二维数值分析模型,重点分析了新建桥梁承台基坑开挖支护对周边场地地表变形和既有桥梁结构变形的影响。研究表明:近接既有桥梁结构的新建桥梁承台基坑开挖施工对周边土层的影响主要原因是开挖施工过程引起地表沉降,地表沉降量在基坑两侧呈非对称分布;承台基坑开挖对既有桥梁的水平向和竖向变形都在安全可控范围内,主要影响既有桥梁的水平向变形。

In recent years,to solve the problem of urban traffic congestion,the construction of urban elevated expressway network has developed rapidly,and the construction projects close to the bridges are increasing day by day.The impact of foundation pit excavation on adjacent existing bridges has become an important issue of concern in foundation pit construction.The ABAQUS finite element analysis sofware is used to establish a two-dimensional numerical analysis model based on the bridge engineering case of a newly-built bridge spanning the rail transit.The impact of the excavation and support of the newly-built bridge base slab foundation pit on the surface deformation of the surrounding places and the deformation of the existing bridge structure is emphatically analyzed.The results show that the main influencing reason of the foundation pit excavation of the new-built bridge base slab close to the existing bridge structure on the surrounding soil layer is the surface settlement caused by the excavation process.The surface settlement is distributed asymmetrically on both sides of the foundation pit.The horizontal and vertical deformations of the existing bridge resulted by the excavation of base slab foundation pit are in a safe and controllable range,which mainly affects the horizontal deformation of the existing bridge.