基于点云强度特征与霍夫直线检测的地铁盾构隧道环缝识别与环间错台检测方法

A method for identifying circumferential joints and detecting inter-ring misalignment in metro shield tunnels based on point cloud intensity features and Hough line detection

  • 摘要: 地铁盾构隧道管片环间错台的高效精准检测对结构安全至关重要。针对现有移动激光点云检测方法依赖螺栓孔、灰度图像辅助识别且处理流程繁琐等问题,基于三维激光点云反射强度特征与霍夫直线检测,提出一种环缝识别与环间错台量计算方法。该方法将三维点云展开为二维平面,通过点云反射强度筛选结合霍夫变换直接定位点云环缝,采用随机抽样一致性与最小二乘相结合的两阶段椭圆拟合策略抑制附属设施噪声干扰,利用断面套合完成错台量计算,并基于某地铁盾构隧道点云数据对该方法进行验证。结果表明,该方法环缝定位平均绝对误差为3.32 mm、均方根误差为4.69 mm;基于60组固定角度错台测点的检测结果,其平均绝对误差为1.028 mm、均方根误差为1.296 mm、95%分位误差为2.484 mm,最大错台量复核结果显示,最大绝对误差为3.3 mm。

     

    Abstract: Efficient and accurate detection of inter-ring misalignment in metro shield tunnels is essential to structural safety. Existing detection methods based on mobile laser scanning point clouds rely on bolt holes or grayscale images to assist circumferential joint identification and involve cumbersome processing procedures. To address these limitations, a method for identifying circumferential joints and calculating inter-ring misalignment is proposed based on the reflectance intensity features of three-dimensional laser point clouds and Hough line detection. In this method, the three-dimensional point cloud was unwrapped onto a two-dimensional plane; circumferential joints were directly located in the point cloud by combining reflectance intensity filtering with the Hough transform; noise from ancillary facilities was suppressed using a two-stage ellipse-fitting strategy combining Random Sample Consensus with least squares-fitting; and inter-ring misalignment was calculated through cross-section matching. The method was tested and validated using point cloud data from a metro shield tunnel. The results show that the method yields a mean absolute error of 3.32 mm and a root-mean-square error of 4.69 mm in circumferential joint localization. For 60 sets of misalignment measurements taken at fixed angular positions, the mean absolute error, root-mean-square error, and 95th-percentile error are 1.028 mm, 1.296 mm, and 2.484 mm, respectively. The verification results for the maximum inter-ring misalignment that the maximum absolute error is 3.3 mm.

     

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