预应力混凝土连续箱梁顶推施工监测

Monitoring on Incremental Launching Construction of Prestressed Concrete Continuous Box Girder

依托一预应力混凝土连续箱梁跨既有线路顶推施工工程,针对工程特点制定了各施工阶段的监测方案,测试了从梁体浇筑阶段的预应力张拉至落梁阶段全施工过程中结构的应力及变形。监测结果表明:预应力张拉阶段梁体张拉效果满足设计要求;顶推系统工作正常,受力状态与计算值吻合良好;顶推阶段梁体和导梁左右侧受力存在一定的不均匀性,但均在安全范围之内;通过监测数据对梁体进行纠偏,使得整个顶推过程中梁体横向偏位很小,基本按照设计轨迹以曲线路径行走;落梁阶段梁体累积应变较小,落梁过程中梁体未产生内力。

The research is focused on the incremental launching construction of a prestressed concrete continuous box girder across existing line.A targeted monitoring scheme is developed for each construction stage.Stress and deformation are monitored during the entire construction,starting from prestress tension after concrete cast till girder drop.The recorded results show that the prestress tension meets the design requirement.The incremental launching system works well,leading to good performance in accordance with the calculation.The behaviors of the girder and the guide beam at both sides are different although the difference is within the safety limit.The girder is adjusted according to the monitoring.In this way,the girder lateral deviation is small during the entire incremental launching construction,and the curved path is the same as the design.At the stage of girder drop,the accumulated strain of the girder is small,and no inner force is caused.