Application of Long Distance Microscope and Three-Dimensional Laser Scanner in Tunnel Section Detection

  • Xiaodong Wang


Tunnel construction in China has attracted worldwide attention in recent years, which is of large scale and difficult. The main potential safety hazard in engineering is the stability and safety of surrounding rock. The traditional surrounding rock monitoring method is to bury fixed points on the tunnel wall, and use total station, level and convergence meter to measure them, so as to obtain the geometric deformation. But the disadvantage is: the measurement time is long, the automation is low, and it can not be monitored remotely and non-contact measurement. The section is replaced by several points on the section, and the whole deformation of the tunnel is replaced by the local deformation reflected by the monitoring section. The traditional method of tunnel deformation monitoring is mainly to extract the data of some points and sections, which has some shortcomings such as large workload, low efficiency and few data. Long-distance microscopy and three-dimensional laser scanner technology can integrate tunnel safety and quality information. One scan can accurately establish the three-dimensional vector model of the tunnel, and accurately obtain the overall deformation and contour information of the tunnel. Based on Tonglu Tunnel, the application of long-distance microscope and three-dimensional laser scanner in deformation monitoring of mountain tunnels is studied. The following conclusions are drawn: when the incident angle of laser scanning is greater than 60 degrees, the scanning error increases sharply, and the maximum distance between stations can be determined according to the incident angle and the inner diameter of tunnel; in order to reduce the mode caused by the accumulative splicing error of tunnel. The reliability of monitoring data can be improved by using single point area analysis method, and the three-dimensional deformation, support invasion limit and thickness of secondary lining can be quickly evaluated by using point cloud and model socket technology, which greatly improves the efficiency of data acquisition and analysis of tunnels.