沪通长江大桥主航道桥钢桁梁制孔精度控制

Precision Control for Holes Made in Steel Truss Girder of Main Navigational Channel Bridge of Hutong Changjiang River Bridge

沪通长江大桥主航道桥为主跨1 092m的双塔三索面斜拉桥,采用3片"N"形主桁结构,钢桁梁采用整节段架设方案,节段内焊接、节段间栓接的组合连接方式。为确保钢桁梁制孔精度并消除后续焊接收缩影响,通过对杆件状态钻孔、桁片或节段状态钻孔2种方案比选,确定了在杆件状态钻孔并配合节段连续匹配制造的总体方案。钻孔时,普通箱形、工形杆件采用单龙门数控钻床钻孔;整体节点杆件采用双龙门三维数控钻床钻孔,对于无法使用双龙门三维数控钻床两端同时钻孔的上弦杆采用双龙门三维数控钻床配合U形样板钻孔。实践表明,该控制技术有效保证了制孔精度。

The main navigational channel bridge of Hutong Changjiang River Bridge is a twopylon cable-stayed bridge with a main span of 1 092 mand with three cable planes.The main girder consists of three N-shaped trusses.The steel trusses were erected by segmental construction method,the members in each segment were welded and segments in turn were bolted together.To ensure the steel truss perforation precision and eliminate the subsequent influences from welding shrinkage,the scheme of perforating prior to the assembly of the members and coordinated segmental continuous matching fabrication was determined by the comparison of the two schemes of perforating ahead of the member assembly and perforating in the truss blocks and segments.By the effective control of the dimension precision,member assembly,welding and adjusting,to ensure that the dimension precision of the members（the key members includes the diaphragms,gusset plates and vertical plates）meet the requirements.During the perforation,the single-axis gantry CNC drill machine was used to make holes in the common box and I members,and the two-axis three-dimensional CNC gantry drill machine was used to members with integral panel points.While,for the upper chord where the two-axis three-dimensional CNC gantry drill machine cannot be used to make holes at both ends in parallel,the U-shaped samples were used to assist.The engineering practice proves that the control technique effectively guarantees the perforation precision.