临时墩不均匀竖向变形对顶推施工影响分析

Analysis of influence of uneven vertical deformation of temporary pier on incremental launching construction

以112 m简支钢箱拱桥步履式多点顶推施工过程分析为背景,利用有限元软件Midas Civil建立了临时墩和顶推模型,结合现场监测数据,分析了支点刚度和临时墩不均匀沉降对钢箱拱顶推施工的影响。发现支点刚度相差过大和临时墩不均匀沉降会引起支点处梁体竖向强制位移,甚现出现“支点脱空”现象,导致主梁和导梁应力增大,并提出采用千斤顶反向预压提前消除临时墩非弹性变形,进一步分级抽垫钢板精调墩顶标高的解决方案。

Based on the analysis of multi-point incremental launching construction process of 112m simply supported steel box arch bridge,the model of temporary pier and incremental launching is established by using the finite element software MIDAS civil.Combined with the field monitoring data,the influence of fulcrum stiffness and uneven settlement of temporary pier on incremental launching construction of steel box arch bridge is analyzed.It is found that the large difference in the stiffness of the fulcrum and the uneven settlement of the temporary pier will cause the vertical forced displacement of the beam body at the fulcrum,and even the phenomenon of"fulcrum disengaging",which leads to the increase of the stress of the main beam and the guide beam.It is proposed that the non elastic deformation of the temporary pier can be eliminated in advance by using jack reverse preloading,and the elevation of the pier top can be adjusted accurately by using the stepped cushion steel plate.