Research on convergence analysis method of metro tunnel section--Based on mobile 3D laser scanning technology

The protection and monitoring of subway tunnels have always been an important guarantee for the safe operation of urban rail transit. The current monitoring of tunnel deformation and convergence relies on traditional technology methods such as convergence meters and electronic total stations. Although the 3D laser scanning method of stationary station setup and station-to-station splicing of monitoring station is gradually becoming mature, the error accumulation and slow operation efficiency brought by station-to-station splicing are still the bottleneck of subway tunnel protection and monitoring. Based on the analysis of the principles and advantages of mobile 3D laser scanning technology, this paper deeply studies the mobile 3D laser scanning technology for rapid collection of point cloud data in subway tunnels, proposes an improved RANSAC algorithm based on the tunnel ellipse parameter model, and extracts metro tunnel deformation information through denoising and fitting of the tunnel cross section point cloud data, achieving convergence analysis of metro tunnel section. The results show that this method can quickly and accurately obtain tunnel section data, which provides a new and efficient technical approach for subway tunnel protection monitoring.