西湖冲特大桥主桥结构设计关键技术

Key Technologies for the Main Span Design of Xihuchong Extra Large Bridge

新建黔张常铁路西湖冲特大桥位于武陵山区,主桥采用60m+2×100m+60m连续梁,由于谷深、墩高,主桥抗推刚度满足行车要求较困难,边跨现浇段支架搭设、预压施工风险高。设计中采用中墩固接、边墩及次中墩设竖向支座的连续刚构体系解决了抗推刚度的问题,先中跨合龙、后边跨悬浇至边墩顶、最后在墩顶现浇剩余部分的工法取消了边跨现浇支架,规避了预压施工风险。

Located in Wuling Mountain area,Xihuchong Extra Large Bridge is a continuous bridge with main spans of 60 m+2×100 m+60 m.Because of high piers and steep slope,main span's anti-pushing rigidity is difficult to satisfy under live load,and the cast-in-place side span scaffolds'construction risk is high to build and preload.A continuous rigid frame system with middle pier rigid connection,other piers with vertical supports is designed to solve stiffness problem.The following construction sequence is as follow,firstly is the closure of the main span is the first order,then is the casting of side spans by cantilever from the center to both sides,finally is the concreting construction of the remaining part at the top of the pier.These design thoughts have important significance for mountain continuous bridge design by improving anti-pushing rigidity and reducing the side span scaffolds construction risk.