望东长江公路大桥关键测量技术

Key Surveying Technique for Wangdong Changjiang River Highway Bridge

望东长江公路大桥主桥为(78+228+638+228+78)m混凝土PK箱组合梁斜拉桥。为准确控制主桥成桥线形,实施高精度测量技术,主桥开工前布设6座混凝土强制归心观测墩,与前期设计交桩点一起作为首级控制网点;建立桥轴坐标系,采用主桥里程桩号和桥轴线偏距作为坐标数据,实施时用图纸设计坐标和里程桩号求取施工控制网与桥轴坐标系的转换关系式;采用GPS水准法进行跨河水准测量;采用Leica TCA2003全站仪测边后方交会方法和三等三角高程测量往返测方法进行钢锚梁及索导管定位;塔柱施工测量主要控制钢护筒偏差、立模偏差、塔柱变形控制等满足精度要求;主桥线形控制主要为轴线及高程控制测量。实践表明,各项测量技术在实践中获得了良好的效果,保证了大桥准确对接。

The main bridge of Wangdong Changjiang River Highway Bridge is a steel-concrete composite girder cable-stayed bridge with span arrangement of（78＋228＋638＋228＋78）m.The steel box girder adopts the passo-kennewick（PK）section.To accurately control the completed geometrical shape of the main bridge,the high-precision surveying technique was implemented.Before the construction of the main bridge,six concrete piers were prepared for forced centering survey,forming the first-grade controlling network together with the previously designed benchmarks.The coordinates of the bridge axis were set,using the mileage numbers of the piers of the main bridge and the eccentricity of the bridge axis as the coordinate data.When implemented,using the designed coordinates on the drawings and the mileage numbers of the piers to obtain the conversion formulas of the construction control network and the coordinates of the bridge axis.The GPS leveling process was used to survey the river-crossing levels.The steel anchoring beams and prestressing tendon ducts were positioned by using the Leica TCA2003 total station to do sideback intersection survey and the to-and-fro trigonometric leveling.The deviation of the steel casings and vertical formwork and the control of the pylon column deformation meet the precision requirements.Axis and elevation control are main issues in the measurement of the main bridge geometry.The engineering practice proves that each measuring technique achieves sound effect in the practice,ensuring the precise butt-joint of the bridge.