悬浇箱梁施工中悬浇块件偏转问题分析及解决方案

Analysis and Solutions on Cantilever Casting Block Deflexion in Cantilever Casting Box Girder Construction

京杭运河特大桥主桥上部结构为(54+90+54)m三跨变截面悬浇预应力混凝土连续箱梁,采用挂篮进行施工。悬浇箱梁施工中右幅施工至8#块件,经过监控测量发现8#块浇注前后挂篮沉降与之前悬浇块段变化趋势不一致,同时对其余块件也进行了观测,发现边跨侧其余块件均有不同程度的沉降,同时结合8#块未浇注时各个块件浇注后与预应力张拉后的数据分析,发现7#块边跨侧浇注前后挂篮有沉降,经过上述原因分析推断该T构已经存在偏转的趋势。根据上述发生的情况及时进行偏转问题分析并提出了具体解决办法,在后续施工中桥梁线形顺畅,结构受力满足要求,结构整体稳定。可以作为同类型挂篮悬浇施工经验参考,如出现类似现象也可参照此解决方案。

The main bridge upper structure of Beijing- Hangzhou canal grand bridge is（ 54 ＋ 90 ＋ 54） m three- span variable cross- section cantilever casting prestressed concrete continuous box girder which adopted cradle in construction. The right side construction of cantilever casting box girder extended to 8 # block,through monitoring and measurement we found that the cradle settling variation tendency of the 8# block before casting and after is inconsistant with the previous cantilever casting block section,in the mean time,we have monitored other blocks and found that other blocks on the sidespan also have settlement in varying degrees. In the mean time,combining with the analysis on data after casting and prestressed tension of other blocks without casting the 8 #block,we found that settlement appeared in cradle before and after casting 7# block of sidespan. Through analysis on the above reasons,conclusion can be made that there is tendency of deflexion in the T structure. According to the situations happened above,we have carried out analysis on the deflexion problem and proposed detailed solutions in a timely manner. In the following construction,the profile of bridge is smooth and the structure stress can meet the requirements and the structure is generally stable. This study may serve as the construction experience reference for the cantilever casting construction of the same type and the solution is appliable for the similar problem when it happens.