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[Objective] The phenomenon of segment dislocation is prevalent in shield tunnel lining, thereby affecting the structural safety and service performance of tunnels in severe scenarios. Manual measurement of segment dislocation is subjective and time-consuming, while automated methods, such as 3D laser scanners, are notonly expensive but also susceptible to environmental conditions. In recent years, advancements in camera technology and deep learning algorithms have significantly propelled the development of computer vision applications in civil engineering monitoring and inspection. Binocular vision technology has been utilized in crack detection and engineering quality evaluation due to its cost-effectiveness and reliable accuracy. This study introduces binocular vision technology to enable accurate measurement of segment dislocation. [Methods] The internal and external parametersof consumer-grade binocular cameras are initially obtained through a calibration experiment, followed by capturing binocular images of the segment joints. The accurate disparity information between the left and right images is further calculated using a deep-learning stereomatching algorithm. Finally, a camera attitude correction method is proposed to calculate the segment dislocation accurately. The primary challenge in camera attitude correction is determining key points on the segmentsurface without evident texture features. Therefore, a series of image processing techniques, such as graying, binarization, dilation, erosion, and target localization, are initially employed on the left photo to automatically identify the location of the segment joint. Then, the parallel thinning algorithm is applied to extract the skeleton of the segment joint (reduce the segment joint width from multi-pixel to single-pixel). The pixel coordinate data along the skeleton are extracted, and the least squares method is used to fit a straight line to the skeleton. Furthermore, the straight lines are shifted and flipped to form latitude and longitude lines, allowing the pixel and camera coordinates of the crossing point (key point) to be calculated in accordance with the triangulation principle. Finally, the segment coordinate system is established using these key points, and the actual segment dislocation is computed. [Results] Field tests on the construction site of the shield tunnel were carried out to evaluate the efficiency of the proposed approach. Results were drawn as follows: (1) The calculation results from the vertical shooting of the binocular camera, after camera attitude correction, showed better consistency than the segment dislocation measurement via weld seam gauging. The specific performance demonstrated that the absolute error did not exceed 1.0 mm, andthe overall processing time for the segmented image was approximately 10.00 s. (2)In multiple rounds of tests with left-leaning or right-leaning shooting scenarios, when the attitude angles of camera coordinate system relative to the segment coordinate system around its own Xc axis and Yc axis were in the ranges of(180.00±15.00)° and ±20.00°, respectively, the proposed method effectively corrected the calculation results with strong robustness. [Conclusions] By combining deep learning algorithms with traditional image processing techniques, binocular vision technology is used to achieve rapid and accurate measurement of segment dislocation. This approach provides a reference for tunnel engineering inspection. © 2025, Tsinghua University. All rights reserved.
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Journal of Tsinghua University
ISSN: 1000-0054
Year: 2025
Issue: 7
Volume: 65
Page: 1359-1368
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ESI Highly Cited Papers on the List: 0 Unfold All
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30 Days PV: 7
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