Research Of Deformation Of High Voltage In Subsidence Area Based On Point Cloud Data

In recent years,due to the technical advantages of non-contact measurement methods and the rapid and accurate acquisition of geometric information on the surface,three-dimensional laser scanning technology is developed rapidly and its application is increasingly widespread.Research on point cloud data is increasingly mature.As the important component of transmission line,the high voltage tower in mining area is related to the normal operation of transmission lines and the safe operation of industrial and mining enterprises.However,in the process of development and utilization of underground coal resources,the original stress balance of underground rock mass and soil mass would inevitably be destroyed,which caused surface subsidence and threatened and endangered the high-voltage transmission towers and lines passing or located in the mining area.Even the surface subsidence would lead to the collapse of high voltage tower,broken lines and other serious security incidents.It is of great significance to carry out deformation monitoring of high voltage line tower and evaluate the safety status of high voltage line tower.The deformation status of the high-voltage was evaluated from the whole and the part separately,based on the point cloud data of high-voltage scanned by three-dimensional laser scanner at different times.On the whole,the horizontal section method is proposed to calculate the tilt deformation.the system error of the horizontal section method is analyzed and calculated and the error compensation formula is derived to obtain more accurate tilt.In the local part,the feature point-climbing nail end point was extracted by neighborhood exploration based on the extracted tower leg cloud of point of high-voltage,the same name feature point of multi-period data was compared to obtain the displacement of feature point.The method of PCA was used to find out the area of deformed angle steel and analyzed the deformation.The specific research contents were as follows:1 The development of 3D laser scanning technology and the common method of processing point cloud were analyzed.The classification and technical principle of three-dimensional laser scanner was summarized.The current research status of deformation monitoring of high voltage was studied and the advantages and disadvantages of various methods were compared.The advantages of using 3D laser scanning technology for deformation monitoring of high voltage towers were summarized.2 The three-dimensional optical surface scanning system and the three-dimensional optical photogrammetric system were introduced,and the high voltage tower model was made to simulate the rigid tilt deformation of the high voltage.The data of point cloud and image of the model tower,before and after tilting,were respectively obtained by the two kinds of measurement systems.The horizontal section method was put forward and was used to calculate the inclination of model tower.The acquired data were analyzed and the feasibility of the horizontal section method for calculating the tilt of the high-voltage was verified.3 The method of collecting point cloud data of high voltage was discussed in this paper and the source of error of point cloud data was analyzed.The high quality data of point cloud of high voltage was obtained after splicing and denoising.The horizontal section of high-voltage point cloud was processed,the points of corner and center were calculated by the step of the boundary point cloud extraction,boundary point cloud segmentation,the boundary point cloud straight line fitting.By calculating the ratio of the deviation between the delaminating surface patch and the bottom patch to the height of the patch,the inclination of the patch can be obtained.The error of horizontal section method was analyzed and the error calculation formula was derived.4 The straight line equations of the quadrangular line were obtained according to the intersection point of each patch,and then set the buffer zone to extract the ridge point cloud of the high voltage tower(including the climbing nail and part of point cloud of the angle steel connected to the tower ridge point cloud).Setting the grid size to build a space bounding box for the ridge point cloud,and the climbing nail cloud were divided into the adjacent space grid.Explore the neighborhood of the spatial grid,extract the point cloud that meets the requirements,regard the center point of the point cloud as suspected feature points,and set the threshold to extract the feature point-climbing nail endpoint.At last,compare the multi-period feature points to find the displacement.5 Angle steel is an important component of the high voltage tower,the deformation of local angle reflects the deformation of the tower.The point cloud were divided into different grid.Regard the point cloud in same grid as a neighborhood set.The curvature of the neighborhood set in each grid was calculated based on the PCA algorithm,then the point cloud with larger curvature was extracted,that is,deformation of the angle of the site,and then analyzed the deformation.