大跨度连续刚构柔性拱组合桥施工控制

宜万铁路宜昌长江大桥主桥为(130+2×275+130) m连续刚构柔性拱组合桥,主梁采用单箱双室截面,拱肋采用钢管混凝土桁架拱.该桥采用"先梁后拱"法施工,其施工控制的难点和重点为主梁两合龙段同时对顶合龙与两跨拱肋竖转合龙,施工控制的内容主要包括线形控制和应力监测.采用预测控制法对施工误差进行分析、识别、调整;通过3种有限元模型对比,适当修正主梁预抛高值.施工过程中的线形和应力监控结果表明,主梁和拱肋成桥线形误差均控制在允许范围内,结构应力满足设计要求,施工控制效果良好.

Construction Control of Long Span Hybrid Bridge of Continuous Rigid Frames and Flexible Arches

The main bridge of Yichang Changjiang River Bridge on Yichang-Wanzhou Railway is a long span hybrid bridge of continuous rigid frames and flexible arches with span arrangement (130+2×275+130) m. The main girder of the bridge is designed as the double-cell and single box cross section and the concrete-filled steel tube truss arches are used for the arch ribs. The bridge is constructed by the method of "erecting the girder first and the arch ribs late", of which the difficult and critical points of the construction control are that the two closure segments of the main girder will be closed in a way of simultaneous opposite jacking and the arch ribs of two spans of the bridge will be closed in a way of vertical rotation. The construction control mainly incorporates the geometric control and stress monitoring. The prediction-control method is used to analyze, recognize and adjust the construction errors and the pre-camber values of the main girder will be appropriately modified by the comparison of the three kinds of the finite element models. The results of the geometric control and stress monitoring in the construction indicate the geometric errors of the main girder and arch ribs of the completed bridge have been all controlled within the allowable range, the structural stress can satisfy the design requirements and the construction control is effective.