Topcon Soga GTL-1200 full-station scanner is applied to the structural safety inspection of Xiamen Metro

As the major artery of urban transportation, the safety of the subway is of vital importance. With the development of technology, 3D laser scanning technology has demonstrated outstanding performance in the field of safety inspection of subway tunnel structures, providing a solid technical guarantee for the safe and stable operation of subways

In the high-precision measurement and in-depth data analysis of the construction period of metro tunnels and their key internal areas, 3D laser scanning technology, with its characteristics of high efficiency, comprehensiveness, and saving of human and material resources, has become the preferred solution for modern metro tunnel safety inspection. Compared with traditional measurement methods, three-dimensional laser scanning technology demonstrates unparalleled superiority in complex environments with low illuminance, high humidity and limited operation time Windows.

Technical solution

1

Set up a station

By using the control points that have been set up in the tunnel, the GTL-1200 full-station scanner is set up at an appropriate position for leveling, and the station is set up by the rear intersection method.

2

"Scan"

After the station setup is completed, enter the scanning module, select "Panoramic Scan", choose "Precision Measurement" for the scanning resolution, click "Start Measurement", and the scanning will be completed when the progress bar reaches 100%.

The GTL-1200 can be scanned in the above-mentioned way, and each station can be completed within 2 minutes at the fastest.

Indoor process

Data import and export

The scanned data of GTL-1200 is directly stored in the memory card and does not need to be manually exported.

2. The Collage professional software can be utilized to perform data denoising processing and format conversion on the collected point cloud data. One-click import of multi-station data into the software and one-click data noise reduction processing. The processed point cloud data supports export to various common point cloud formats (LAS, E57, PTS, XYZ, etc.).

Line design information input

Based on the client's design route, section and other information, the design route is edited on the online platform of the point cloud section processing software. After the input is completed, it is synchronized to the computer client for data processing (it also supports common problems in metro line design such as broken links).

Scanning results and analysis

Import the processed high-quality point cloud data into the software and conduct the following key analyses:

Centerline calculation and comparative analysis

Automatically generate the centerline of the tunnel and conduct precise comparison and analysis with the designed centerline to assess the offset of the tunnel axis, providing a basis for the safety assessment of the tunnel structure.

Section extraction and clearance analysis:

The tunnel section is automatically extracted based on the preset section mileage, and the section clearance analysis is automatically conducted. Eight points are measured as required in the section. The specific locations of the measurement points are: one point each on the bottom plate surface and top plate bottom, and three points each on the left and right sides. The result data of line and slope adjustment is automatically generated.

Ellipticity assessment

Ellipticity calculation is carried out on the tunnel cross-section to assess the deformation of the tunnel cross-section and detect the morphological changes of the tunnel structure during the construction process.

In subway scanning work, the station setting function of the GTL-1200 full-station scanner can effectively avoid the splicing error of data from each station. Its excellent scanning speed can significantly reduce fieldwork time and minimize the impact on on-site work. The point cloud section processing software it is paired with can reduce noise with one click and generate diverse reports, effectively improving work efficiency. The scanning data and results can be operated in real time in 3D through the point cloud cross-section processing software, allowing for data viewing anytime and anywhere.