云桂铁路南盘江特大桥扣锚索系统施工设计

南盘江特大桥是云桂铁路全线的重难点控制性工程,也是世界铁路中斜拉扣挂+分环分段组合法模注拱圈混凝土最大跨度的混凝土拱桥,主桥为单跨416m上承式钢管外包混凝土拱桥。扣锚索系统主要由扣塔、扣点、扣索、锚索及锚碇系统组,扣塔由主体5号、6号交界墩、0号段及其上部钢塔组成;扣点利用Q345B钢板在劲性骨架上弦管节点位置焊接而成;扣锚索均采用75 mm(j15.24,Rby=1 860 MPa)钢绞线束;锚碇采用岩锚和桩基承台锚碇两种形式。利用此系统进行劲性骨架单节段整体斜拉扣挂悬臂拼装、斜拉扣挂+分环分段组合法模注外包混凝土,为解决高山深谷条件下大跨度钢管外包混凝土拱桥的安全快速施工提供了参考。

Construction Design for Fastening-Anchoring Cable System of Nanpanjiang Bridge on Yunnan-Guangxi Railway

As a super major bridge,Nanpanjiang Bridge is an important and difficult control project on Yunnan-Guangxi Railway.With the longest span in this kind of bridges in the world,it belongs to the concrete arch bridge with casting arch ring concrete which was erected by cable-stayed fastening-hanging method plus piecewise combination method,and its main bridge is a deck type concrete-encased steel tube arch bridge with a span of 416 meters.Its fastening-anchoring cable system was made mainly from several subsystems,including the fastening tower,fastening point,fastening cable,anchoring cable and anchorage device.The fastening tower was composed of No.5 and No.6 border pier,No.0 segment and upper steel tower.Q345B steel plate was welded at the tube joint of upper chord of the stiff frame and then was taken as the fastening point.Both the fastening cable and the anchoring cable were composed of 75(j15.24,Rby=1 860 MPa) steel stranded wires respectively.Two anchorage methods including rock anchorage and pile cap anchorage were employed.With this system,the construction of the stiff frame by segmental cable-stayed fastening-hanging cantilever assembling method,and the construction of casting arch ring concrete by cable-stayed fastening-hanging method plus piecewise combination method could all be carried out.This system also can serve as a reference for safe and fast construction of long-span concrete-encased steel tube arch bridge under the conditions of high mountains and deep valleys.