Precise Positioning Method of Moving Laser Point Cloud in Shield Tunnel Based on Bolt Hole Extraction

Abstract

Mobile laser scanning technology used for deformation detection of shield tunnel is usually two-dimensional, which is expanded into three-dimensional (3D) through mileage, resulting in low positioning accuracy. This study proposes a 3D laser point cloud positioning method that is divided into rings in the mileage direction and blocks in the ring direction to improve the positional accuracy for shield tunnels. First, the cylindrical tunnel wall is expanded into a plane and the bolt holes are extracted using the self-adaptive parameter adjustment cloth simulation filter (CSF) algorithm combined with a density-based spatial clustering of applications with noise (DBSCAN) algorithm. Second, the mean-shift algorithm is used to obtain the center point of the bolt hole, and a model is designed to recognize the center point of different splicing blocks. Finally, the center point is combined with the standard straight-line equation to fit the straight-line positioning seam, achieving an accurate ring and block segmentation of a shield tunnel as a 3D laser point cloud. The proposed method is compared with existing methods to verify its feasibility and high accuracy using the seams located by the measured tunnel point cloud data and in the measured point cloud. The average differences between the circumferential seams positioned using the proposed method and those in the point cloud at the left waist, vault, and right waist were 3, 4, and 5 mm, respectively, and the average difference between the longitudinal seams was 3.4 mm The proposed research method provides important technical and theoretical support for tunnel safety monitoring and detection.

A Handheld LiDAR-Based Semantic Automatic Segmentation Method for Complex Railroad Line Model Reconstruction

“…However, they typically have low requirements for detailed results. When faced with the separation of specific structures, such as railroad vegetation filtering and shield tunnel bolt-hole extraction [27,58], a higher level of detail is required, necessitating adaptive modifications to the CSF method. Despite these adaptations, these methods still primarily focus on extracting a particular type of outward protruding structure from the space, which demonstrates the versatility of the approach.…”

“…In the railroad domain, point cloud data collection is commonly achieved through the utilization of inspection vehicles mounted on the tracks [27,28]. However, such equipment is often associated with substantial costs and operational complexities as it necessitates running on the steel rails and requires obtaining approval for a "Skylight Period" from railroad operators.…”

Experiment and Application of NATM Tunnel Deformation Monitoring Based on 3D Laser Scanning

“…Based on mobile laser scanning technology, many scholars at home and abroad have designed building information models (BIMs) to develop deformation monitoring systems for tunnels or other retaining structures [10,11]. At the same time, 3D laser scanning technology can not only design the structural positioning and orientation system [12][13][14][15][16][17] but also create a 3D building information model (BIM) [18,19] based on the orientation system. In fact, by optimizing the deformation data extraction and improving the registration algorithm [20][21][22][23], the accuracy of tunnel 3D modeling and deformation monitoring can be efectively improved [14,[24][25][26].…”

Deformation Detection of Mining Tunnel Based on Automatic Target Recognition

“…Zhao et al [30] used a point cloud to generate an image and manually mark the circumferential seams, and then used symmetrical section superposition to analyze the dislocation between the rings. Ji et al [31] used the spatial distribution characteristics of bolt holes to locate the seams and divide the tunnels into rings and blocks, providing a good precondition for the deformation detection of shield tunnels. The mining method tunnel does not have the regular segment structure of the shield tunnel.…”