Objective In view of the poor real-time performance, high cost and low efficiency of tunnel deformation monitoring methods in China, it is necessary to effectively improve the efficiency of tunnel ...deformation monitoring. Hence, a monitoring and measuring method of tunnel deformation based on onboard LIDAR (light laser detection & ranging) is proposed. Method The LIDAR sensor is used to scan and collect the three dimensional data of the whole tunnel section, and the total least squares is used to adjust the cloud data of the tunnel points and fit the surface. The deformation of tunnel section is analyzed according to the fitted ellipse parameters to realize rapid dynamic inspection of the tunnel deformation. Result & Conclusion The experimental results show that with this method the tunnel full section data can be obtained quickly and accurately. The tunnel deformation condition can be effectively obtained through the data processing and analysis with total least squares, basically realizing the dynamic real-t
The use of terrestrial laser scanning (TLS) point clouds for tunnel deformation measurement has elicited much interest. However, general methods of point-cloud processing in tunnels are still under ...investigation, given the high accuracy and efficiency requirements in this area. This study discusses a systematic method of analyzing tunnel deformation. Point clouds from different stations need to be registered rapidly and with high accuracy before point-cloud processing. An orientation method of TLS in tunnels that uses a positioning base made in the laboratory is proposed for fast point-cloud registration. The calibration methods of the positioning base are demonstrated herein. In addition, an improved moving least-squares method is proposed as a way to reconstruct the centerline of a tunnel from unorganized point clouds. Then, the normal planes of the centerline are calculated and are used to serve as the reference plane for point-cloud projection. The convergence of the tunnel cross-section is analyzed, based on each point cloud slice, to determine the safety status of the tunnel. Furthermore, the results of the deformation analysis of a particular shield tunnel site are briefly discussed.
The paper presents the mobile multi-sensor system Orthos Plus for the monitoring and mapping of tunnel walls, a scan data processing method for the evaluation of 3-d tunnel wall displacements from ...subsequent wall scans and, finally, a virtual reality tool supporting the interpretation of data. The measuring system consists of a 3-d laser scanner, a motorised total station and a digital camera that are integrated on a light metal frame that is installed on a mobile platform. It has been designed to perform tunnel measurements most efficiently and to meet the special requirements of tunnels under construction. The evaluation of 3-d displacements is based on a 3-d matching algorithm that takes advantage of the particular conditions of tunnel (shotcrete) surfaces. The virtual reality tool allows viewing of data in a 3-d virtual reality tunnel model and their animation in time and space in order supports understanding in an optimal way. The measuring system Orthos Plus has been developed in the course of a national research project, the 3-d matching method in the frame of the Austrian Christian Doppler Laboratory Spatial Data from Laser Scanning and Remote Sensing and the VR tool in the Austrian COMET K1 Competence Center VRVis Center (www.vrvis.at).
Intelligent total station is the general approach for deformation monitoring of the subway tunnel in current use, but the data size is limited and the labor cost is high during information ...extracting. A method for vertical section abstraction based on 3D point cloud is proposed in this paper, which can be applied for deformation monitoring. This approach includes 3 parts: point cloud registration, tunnel central axis calculation and vertical section abstraction. The central axis of a subway tunnel can be determined through RANSAC algorithm and least square adjustment; the orientation of tunnel firstly has to be adjusted in terms of the central axis, then the data can be fitted by local quadric fitting, which includes constrained least squares algorithm and RANSAC algorithm. The feasibility and accuracy of the proposed method have been verified using the point clouds acquired by RIEGL VZ-400 laser scanner, and the practical significance for applications of 3D laser scanning is reflected to some extent.
In the deformation monitoring of large-section shallow buried tunnels, the traditional monitoring methods are affected by the temporal and spatial effects of tunnel construction, resulting in ...insufficient safety of the monitoring methods. Therefore, a deformation monitoring method based on GNSS technology for large cross-section shallow excavation tunnel is proposed. The GNSS automation equipment and its technology are combined to realize the real-time acquisition of monitoring data, and the displacement trend diagram of monitoring points is displayed. According to the known monitoring parameters, the basis for judging the deformation stability is determined. Combined with the calculation results of tunnel surrounding rock and support structure parameters, the optimal fitting monitoring results are obtained. The experimental results show that the total power factor of the designed large-section shallow buried tunnel deformation monitoring method based on GNSS technology is stable, the monitoring results are basically consistent with the actual tunnel deformation, and its safety has been improved.
A new approach is introduced to measure tunnel deformation by active panorama vision technology aiming at the long-distance tunnel, long maintenance intervals, limited repairing time, a little of ...deformation change of the tunnel. In order to monitor the tunnel deformation information, Firstly, the panoramic scanning image of tunnel section can be directly received when the Active Stereo Omni-Directional Vision Sensors (ASODVS) in the tunnel detection device is going through the tunnel to make a panoramic scanning, then the geometry information of target surface can be analyzed through extracting the reflected laser image from the picture captured, after that, the tunnel is reconstructed using spatial point cloud data, finally, the refactoring tunnel model precision is analyzed. The experimental research shows that the system has the advantages of high speed acquisition, more real-time, more detailed data, high visualization. It can meet the needs of the rapid qualitative and quantitative analysis.
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