复杂曲线钢槽梁跨线顶推施工关键技术: 以响堂铺2号大桥为例

响堂铺2号大桥位于丘陵山区,其下侧需跨既有高速,主梁整体线形呈S型,施工难度较大。其中第一联主梁采用钢-混组合结构,下侧钢槽梁采用步履式顶推施工工艺,临时支架设计为非对称布置。针对此情况,为确保钢槽梁顶推施工的安全性、可靠性,分析了钢槽梁顶推施工的路径以及千斤顶摆放的位置后,通过多种有限元模型的搭建,以顶推过程中的梁体应力及变形模拟计算为依据,为钢管支架结构进行了抗剪优化,并设计出降低主梁弯矩的同时仍可在汇交138°的垫梁及支架上进行落梁的钢导梁。在施工时采用优化后的主梁同步顶推系统对S型主梁进行连续顶推,而提出的导梁上墩保障措施,主梁临时锁定、横向旋转、线形保障等措施在确保施工过程安全性的同时,亦可保障主梁线形的完整平顺。此外现场监测方案,采用几何监测与物理监测相结合的方式,使得实测值与理论值一致性良好,并以此进一步提高施工质量和大桥生命周期内的服役能力。该项顶推施工技术丰富了复杂情况下的桥梁施工技术,也可为今后类似的跨线、S型主梁、钢-混组合梁桥的顶推施工提供参考。

Key Technology of Cross-line Incremental Jacking Construction of Complex Curved Steel Channel Beam : Taking Xiangtangpu No.2 Bridge as an Example

Xiangtangpu No.2 Bridge is located in hilly and mountainous areas. Its lower side needs to cross the existing high-speed. The overall alignment of the main beam is S-shaped, and the construction is difficult. The first joint main beam adopts steel-concrete composite structure, the lower steel channel beam adopts walking jacking construction technology, and the temporary support is designed as asymmetric arrangement. In view of this situation, in order to ensure the safety and reliability of the jacking construction of the steel channel beam, the path of the jacking construction of the steel channel beam and the position of the jack are analyzed. Through the construction of various finite element models, based on the simulation calculation of the stress and deformation of the beam during the jacking process, the shear optimization of the steel pipe support structure is carried out, and the steel guide beam that can reduce the bending moment of the main beam while still falling on the intersection 138 ° cushion beam and bracket is designed. During the construction, the optimized synchronous jacking system of the main beam is used to continuously push the S-type main beam, and the proposed safeguard measures for the upper pier of the guide beam, temporary locking of the main beam, lateral rotation, linear protection and other measures can ensure the safety of the construction process. In addition, the combination of geometric monitoring and physical monitoring makes the measured values consistent with the theoretical values, and further improves the construction quality and the service ability of the bridge life cycle. This jacking construction technology enriches the bridge construction technology under complex conditions, and can also provide reference for the jacking construction of similar cross-line, S-shaped main girder and steel-concrete composite girder bridges in the future.