Application of 3D Laser Scanning Technology in Line and Slope Adjustment of High-speed Railway Shield Tunnels.

Relying on the actual engineering case of Liucun Tunnel of Nanchong high-speed railway, this paper studies the key process of using 3D laser scanning technology in shield tunnel line and slope adjustment measurement. Firstly, the measurement principle of 3D laser scanning technology is introduced, and the analysis is carried out from four aspects: preparation for the operation, external scanning, data processing and comparison of results. In order to avoid cumulative errors when splicing point clouds, a control point-based station splicing method was adopted to splice the 18 stations into a complete 3D point cloud data of 3. 7 km in length. The tunnel section interception parameters were set according to the line design data, and the tunnel center coordinates were obtained by RANSAC method after denoising using a circle curve fitting method based on orthogonal distance regression. Research shows that the accuracy of the tunnel center coordinates detected by 3D laser scanning technology is better than 10 mm, which can meet the line and slope adjustment measurement of shield tunnels. The results of the study show that the 3D laser scanning technology can not only significantly improve the efficiency of work, but the high-density and high-precision laser point cloud obtained can also provide the basic data for a large amount of subsequent work, which has a broad application prospect. [ABSTRACT FROM AUTHOR]