自由设站放样测量在轨道交通连续刚构PC梁架设中的应用

芜湖轨道交通二号线是国内外首次采用跨坐式连续刚构PC梁的轨道交通项目,相较于国内外现有轨道交通项目的跨坐式简支PC梁,在梁体安装精度、线路平顺性控制、施工技术难度等方面均优于跨坐式简支PC梁。介绍了跨坐式连续刚构PC梁架设中自由设站放样测量控制网的测设原理、布点方法及布点形式,利用自由设站放样测量方法设站灵活、放样精度高等特点,结合自主研发的专用放样工装设备,解决了轻轨跨坐式连续刚构PC梁架设中测量精度不稳定、高程上桥困难、作业时遮挡严重、测量人员安全风险大、多榀梁连接平顺性差等测量难题,可将轨道梁中线偏差控制在3 mm以内,轨道梁中心变化率控制在1.5 mm/1.5 m以内,线路超高情况下的角度公差控制在±1/8°以内。实践证明:自由设站放样测量能够满足轨道PC梁精调施工定位的精度要求,且效率高、精度高、安全性高,在同类项目中具有推广和应用价值。

Application of Free Station Lofting Survey in PC Beam Erection of Continuous Rigid Frame in Rail Transit

Wuhu Rail Transit Line 2 is the first rail transit project that uses straddle-type continuous rigid frame PC beams.Compared with the existing straddle-type simply supported PC beams of existing rail transit projects,the installation accuracy of the beam body,the performance control of line smoothness,construction technical difficulty and other aspects of beam in this project are all better.This paper introduces the setting principle,layout method and layout form of control network of the free station setting-out measurement in the straddle type continuous rigid frame PC beam erection.Using the flexible stationing,high laying-out accuracy and other characteristics of free station setting-out measurement method,combined with the special setting-out tooling equipment from independent research and development,the measurement difficulties in the light rail straddle type continuous rigid frame PC girder erection have been solved such as the unstable measurement accuracy,the difficulty of leveling to bridge,the serious occlusion during operation,the large safety risk of the surveyor,and the poor smoothness of the connection of multiple beams.The deviation of the center line of the track beam is controlled within 3 mm,the change rate of the center of the track beam is controlled within 1.5 mm/1.5 m,and the angle tolerance is controlled within ±1/8° in superelevation design of line.Practice has proved that the free station setting-out survey can meet the precision requirements of the track PC beam fine-tuning construction positioning,has high efficiency,high accuracy and high safety,and has the value of promotion and application in similar projects.