Research On Bridge Spatial Deformation Monitoring Method And Application Based On Ground 3D Laser Scanning Technology

As an important part of bridge structural health detection,bridge structural deformation monitoring is an important index for bridge structural bearing capacity evaluation and safety evaluation.At present,the bridge structure deformation measurement still stays in the traditional contact and non-contact single point measurement methods,and these methods generally have the disadvantages of heavy workload,long cycle,cumbersome process,and can only obtain the data of a limited number of monitoring points.The emergence of three-dimensional laser scanning technology breaks the traditional point-to-point measurement theory,makes up for the shortcomings of the existing measurement technology,and can realize the high-precision measurement of the overall spatial geometric state of the bridge.Based on this,this paper applies the ground three-dimensional laser scanning technology to the field of bridge deformation monitoring,starting from controlling the scanning measurement error,optimizing the data processing algorithm,and improving the data processing accuracy,aiming to study the bridge spatial deformation monitoring method based on the ground three-dimensional laser scanning technology,and realize the high-precision quantitative analysis of the bridge structure.The main tasks of this paper are as follows:(1)The principle and characteristics of three-dimensional laser scanning technology are systematically introduced.Aiming at the characteristics of many error factors in scanning measurement,the error sources of scanning measurement are classified and analyzed,and the point accuracy test is designed to explore the influence of scanning distance and scanning resolution on the point accuracy.(2)This paper studies the point cloud data preprocessing algorithm,and improves the point cloud noise reduction algorithm.The traditional ICP algorithm based on featurefree registration is greatly affected by the overlap degree of point clouds,and the registration accuracy is difficult to guarantee.The target feature based registration method is limited by the distance and edge effect.A target feature registration method based on triangular pyramid is proposed,and the accuracy and feasibility of data registration are verified by experiments.(3)The experiment of deformation accuracy is designed,and the Leica stationscan used in the research is analyzed The deformation measurement accuracy of P50 threedimensional laser scanner in different scanning resolutions and different distances is explored.The experiment shows that: under the experimental conditions,using high scanning resolution for deformation monitoring,the mean square error is within 0.1 mm,but with the increase of scanning resolution to a certain extent,the measurement error will increase randomly,and the scanning distance within 100 m has a significant effect on the plane deformation measurement accuracy The overall mean square error is within0.1 mm.(4)Taking the scattered point cloud data of bridge as the object,the basic algorithm of point cloud data segmentation and plane fitting is studied.Combined with the characteristics of point cloud data of bridge structure,the algorithm of feature line extraction and the algorithm of bridge bottom line extraction are studied,and a method of accurate deformation extraction based on sliding window method is proposed,which is applied to the loading experiment of reinforced concrete arch in laboratory.The feasibility of the data processing method is verified by comparing the scanning measurement data with the measured data of dial indicator Reliability and accuracy.(5)Based on the load test project of continuous rigid frame bridge in rail transit,the application of three-dimensional laser technology in bridge deformation monitoring is studied.By using the 3D comparison method between point clouds and the bridge deformation extraction algorithm,the overall spatial deformation analysis and vertical displacement accurate quantitative analysis of the bridge state under different load conditions are carried out,and the overall spatial deformation trend and accurate vertical displacement of the bridge structure are obtained.(6)Through the analysis of the bridge global point cloud by the bridge feature extraction algorithm,the geometric features of the real bridge are obtained,the geometric deviation of the design model is corrected,and the finite element model which conforms to the geometric features of the bridge entity is established.By comparing the measured deformation with the theoretical deformation data,the bearing capacity of the bridge structure is evaluated.The results show that the application of 3D laser scanning technology in bridge deformation monitoring is feasible and has high accuracy.The research shows that by using reasonable deformation monitoring methods to maximize the accuracy of scanning measurement,it can achieve high-precision deformation monitoring and overall analysis of bridge structure.It is feasible to apply 3D laser scanning technology to bridge deformation monitoring,and has the advantages of high precision,integrity,continuity and so on.The successful application of this method is of great significance to the deep application of 3D laser scanning technology in the field of bridge monitoring.