武汉二七长江大桥桥塔索道管精密定位方法

为保证武汉二七长江大桥(斜拉桥)施工时索塔的几何形状及空间位置符合设计规范要求,通过布设精密测量施工控制网、构建三维坐标数学模型完成塔柱索道管定位。步骤如下:在岸上布设3个强制观测墩,和全桥控制网组成高精度加密控制网;在岸上的劲性骨架上安装索道管定位架、焊接索道管调整装置后,整体吊装并调整劲性骨架的位置,完成岸上初定位;在塔柱劲性骨架上设置控制点,建立独立坐标系进行索道管高精度定位测量。精度分析表明,该方法对索道管定位的测量精度完全满足±5mm设计的要求。

Method for Precise Positioning of Cable Ducts in Pylon of Wuhan Erqi Changjiang River Bridge

To ensure that the geometric shape and spatial position of the pylon of Wuhan Erqi Changjiang River Bridge(a cable-stayed bridge) could accord with their design and code requirements in the construction process,the cable ducts in the pylon columns were positioned by the method of setting up the precise survey construction control network and the three-dimensional coordinate mathematic model.The procedures of the positioning of the ducts were specifically as follows: three forced observation pillars were firstly set on the banks and together with the control network for the whole bridge,the pillars would form a highly precise densified control network.On the steel frame skeleton on the bank,the positioning frames for the cable ducts were installed.After the ducts were welded and the positions of the ducts were well adjusted,the whole skeleton was lifted,the position of the skeleton was adjusted and the preliminary positioning of the ducts on the bank was thus completed.Then the control points were set on the skeleton in the pylon,the independent coordinate system was set up to continue the precise survey of the positioning of the ducts.The analysis of the survey precision showed that the positioning precision of the ducts by the method could completely satisfy the design requirement of±5 mm.