Research On The Application Of Bridge Deformation Monitoring Based On 3D Laser Point Cloud Slice Extraction Technology

The emergence and development of 3D laser scanning technology has enriched and expanded the technical means in the field of surveying and mapping.In a noncontact way,the high-density point cloud data of the target body can be obtained in a short time,which can reflect the detailed changes of the target,and is widely used in the field of deformation monitoring.In this paper,we study the bridge deformation monitoring based on bridge point cloud slicing extraction technology,and analyze the application of Wuhan Qingchuan Bridge as an example.The main research contents and results are as follows.(1)The current research status of bridge deformation monitoring and point cloud slicing technology application is summarized,the 3D laser raw point cloud preprocessing process is described,and the error sources,characteristics,effects and countermeasures of 3D laser scanning technology are analyzed.Based on the analysis of 3D laser scanning errors,point cloud accuracy experiments were designed to analyze the influence law of scanning distance and scanning resolution on experimental data.(2)The optimal slicing position,principle and datum acquisition of the bridge point cloud are studied,the current point cloud slicing circle model fitting methods are compared and analyzed,and the ideas of point cloud center coordinate acquisition and central axis extraction after fitting are elaborated for bridge monitoring.The application of point cloud slicing technology in bridge deformation monitoring is also discussed with Wuhan Qingchuan Bridge as an example.(3)Using the coordinate extraction method based on feature point identification for bridge arch section monitoring,the influence of different thickness slices on the experimental results is investigated,and the results show that the selected slice thickness of 5m and the reference plane are sufficient to show the bridge arch deformation area.In order to extract more accurate deformation information,the deformation location interval is carefully divided by 0.5m slice thickness,the calculation can be obtained from the cross-sectional feature point transverse error in0.005 m,longitudinal error in 0.003 m,three-dimensional offset error of 0.0102 m,the subsequent superposition analysis of the two phases of the bridge arch axis,the analysis of deformation information.(4)Bridge deck deflection monitoring was carried out by using point cloud slicing to extract bridge cross-sections.55 cross-sections supporting the bridge deck were selected as the experimental objects,and the coordinates of the section center points were extracted based on the fitting algorithm,and the deflection analysis was carried out by fitting the central axis of the bridge deck.The comparison of deflection deformation between the two periods shows that the elevation deviation is larger and the vertical river surface bends downward in the interval of crossbeam 24#-34#.For the bridge pier verticality monitoring,the center point coordinates extraction method of vertical cylinder fitting was used to extract the center point coordinates of the seemingly circular surface and fit the bridge pier central axis,and the verticality piece deviation was initially analyzed.