Axis Extraction and Inclination Inspection of Bridge Underwater Pile Foundation Based on Sonar Point Cloud

doi:10.3969/j.issn.1674-0696.2026.01.04

Abstract

Abstract: Underwater structures located in deep and turbid waters, facing challenges such as poor accessibility and considerable detection difficulties. To evaluate the stability of bridge underwater foundation and promote the development of inspection technologies, a method for extracting the axis of underwater pile foundation and automatically detecting the inclination was proposed, which was based on underwater sonar point cloud data. The principal component analysis (PCA) method was employed to determine the normal vectors of the point cloud slices of the pile foundations. Subsequently, projection and geometric analysis techniques were combined to extract the spatial coordinates of the pile foundation axis feature points. Then, the RANSAC algorithm was used to fit the axis of the underwater pile foundation, thereby enabling the calculation of pile foundation inclination. The effectiveness of the proposed method was verified through the point cloud models of underwater pile foundation generated by numerial simulation. The research results show that the mean absolute error between the calculated inclination angles of pile foundations and the true values is 0.031°, which indicates that the proposed method can accurately extract inclination angles of pile foundations from point cloud data, possessing good engineering application value. Furthermore, 3D point cloud data of underwater pile groups of certain two Yangtze River bridges are obtained by utilizing the three-dimensional sonar measurement system, by which the deformation detection of actual bridge underwater pile foundations is realized.

Key words: bridge engineering; underwater inspection; 3D sonar; point cloud; pile foundation axis; inclination

摘要： 水下构筑物所处深水、浑水区域，其可达性较差，检测难度较大。为评估桥梁水下基础的稳定性并促进检测技术发展，基于水下声呐点云数据，提出了一种水下桩基轴线提取与倾斜度自动检测的方法。采用主成分分析法(PCA)确定桩基点云切片的法向量；再结合投影与几何分析提取桩基轴线特征点的空间坐标；随后利用RANSAC算法拟合水下桩基轴线，进而计算桩基倾斜度；通过数值模拟生成水下桩基点云模型验证方法的有效性。研究结果表明：桩基倾角计算值与真值的绝对误差均值为0.031°，表明该方法能准确从点云中提取桩基倾角，具备较好的工程应用价值；基于三维声呐测量系统获取某两座长江大桥水下群桩三维点云数据，利用该方法实现了实桥水下桩基变形检测。

关键词: 桥梁工程；水下检测；三维声呐；点云；桩基轴线；倾斜度

CLC Number:

U445.7

LIU Ning1, ZHANG Jiewu2, YAN Jing3, ZHU Yanjie3. Axis Extraction and Inclination Inspection of Bridge Underwater Pile Foundation Based on Sonar Point Cloud[J]. Journal of Chongqing Jiaotong University(Natural Science), 2026, 45(1): 23-29.

刘宁1，张杰武2，严靖3，朱彦洁3. 基于声呐点云的桥梁水下桩基轴线提取与倾斜检测[J]. 重庆交通大学学报（自然科学版）, 2026, 45(1): 23-29.

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