关键词: 桥梁工程； 水下检测； 3D声呐； 点云； 数据处理

Abstract: Due to the perennial erosion of the substructure foundation in complex aquatic environments and the potential impact of drifting objects, wading bridges are prone to developing apparent defects. Therefore, it is essential to conduct regular inspections to assess their safety status. Owing to the limitations of underwater scenarios, conventional damage detection methods are difficult to achieve effective detection of damage. To address this issue, 3D sonar measurement technology was employed for the inspection of underwater foundations of bridges. The basic principles of 3D sonar measurement technology and its basic implementation process for underwater foundations of bridges were introduced, and an integrated processing method covering point-cloud acquisition, data processing and foundation morphology extraction was proposed, so as to generate a three-dimensional point-cloud model that could accurately reflect the apparent characteristics of the foundation. The results indicate that, under complex underwater environmental conditions, the proposed method can effectively achieve three-dimensional shape reconstruction and dimensional measurement for different types of foundations. For large-scale underwater foundations such as caissons and cofferdams, the maximum measurement error is only 7.9%, demonstrating good detection accuracy and engineering applicability. For small-scale components such as pile groups, although the average diameter measurement error reaches 18.2% due to weaker echo signals and sparse point clouds, the proposed method can still satisfy the basic requirements for geometric feature identification and safety assessment of the foundations.

Key words: bridge engineering; underwater inspection; 3D sonar; point cloud; data processing