Abstract:

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.

Key words: datum strand, single-refraction coefficient, sag measurement, trigonometric leveling, suspension bridge