大气折光系数测定及在悬索桥基准索股线形测量中的应用

大跨度悬索桥基准索股跨中位置处于百米高空,如何测得精确的垂度值,对主缆线形进行控制至关重要。本文分析了影响悬索桥基准索股垂度测量精度的主要因素,提出了基于实时大气折光系数改正的单向三角高程的跨中垂度测量新方法。在桥址区建立高精度的高差基准,通过对桥址区的大气折光系数的测定及改正试验,证明该测量方法切实可行。基准索股跨中垂度采用双测站进行测量,当双测站所测同一点绝对垂度互差小于10 mm时,取双测站所测垂度均值作为该点的垂度值。该方法的测量结果达到设计精度要求,对同类工程测量项目有借鉴意义。

Surveying and calculating single-refraction coefficient and using in surveying the linear of datum strand of suspension bridge

The mid-span position of datum strand of long-span suspension bridge is at an altitude of 100 meters, how to measure the verticality accurately for controlling the shape of the main cable. This paper analyzes the influence factors that affect the surveying precision of datum strand erection of suspension bridge, and it introduces a new sag measurement method for the mid-span position that based on the single-refraction coefficient correcting for trigonometric leveling. Establishing high-precision height difference datum in the bridge site area, and experiment that single-refraction coefficient was measured and corrected that proves the surveying method is correct. Two stations are used for the sag measurement of the mid-span position of datum strand, and the value is the average of sag measured at double stations when the difference between them is less than 10 mm. The measurement results of this method meet the requirements of design accuracy,and it has the model significance to the similar project.