Design Scheme And Research Method Of Tunnel Monitoring Based On Point Cloud Data

With the rapid development of transportation,the construction of subway,railway and highway construction is changing with each passing day,and the construction of tunnel engineering is also rising continuously.The quality of tunnel has become the key factor of tunnel construction and line operation.In order to effectively guarantee the safety of people’s lives and property,it is of great significance to monitor the deformation of tunnel engineering in the whole life cycle.With the rapid development of 3D laser scanning technology,as well as its fast speed,good continuity and high precision,it can be widely used in 3D modeling,cultural relic protection and deformation monitoring and other fields..The 3D laser scanner is applied to the deformation monitoring of the tunnel,and de-noising of point cloud data,extraction of the central axis,extraction of continuous section of tunnel,deformation analysis of section,extraction of flat curve elements from a point cloud,entirety superposition and contrast analysis of multi-period point cloud data and so on are focused on.The aim is to set up a perfect model of point cloud monitoring tunnel,so that it can extract the tunnel deformation information more efficiently and comprehensively through point cloud data,and provide a new way for monitoring,acceptance and operation maintenance of tunnel engineering.In this paper,the following work is done from point cloud data processing and tunnel deformation information extraction.(1)Three methods of extracting the axis of the tunnel point cloud are studied and analyzed,and the most suitable and efficient extraction method of the central axis is selected from the three extraction methods.The extraction of the tunnel axis from the 3D point cloud is the basis for the study of tunnel deformation monitoring.The central axis can provide the basis for the extraction of the continuous section of the tunnel in the later period,and can also provide the basis for the extraction of the plane curve elements in the tunnel.(2)The point cloud of the subway tunnel is extracted according to the mileage,and the coordinate transformation of the obtained point cloud data is carried out.The point cloud is projected onto the XOZ surface and noise is removed with the elliptical model.The ellipticity,the length and the half axis and the net space convergence of the section are calculated and analyzed,which analysis the deformation of the tunnel in space is analyzed.In order to better analyze the deformation mechanism of the tunnel section,we can clearly express the deformation rule of the section by expressing the color change value of RGB to the shape variables of the tunnel section.(3)In order to extract the horizontal curve elements of tunnel,a curvature feature algorithm is introduced in this paper.Through the straight line,transition curve and curvature characteristic of circular curve,the horizontal curve of tunnel is roughly segmented.Then according to the continuous iteration of the linear parameters and the circular curveparameters and the orthogonal least square method,the accurate parameters of the flat curve are obtained.(4)In order to make multi phase comparison analysis of road tunnel point cloud data,a fixed base point method is proposed in this paper.This method not only unifies the coordinate system of each phase of the point cloud data of the highway tunnel,but also improves the precision of the coordinate transformation.The superposition of point cloud data after unifying coordinates can not only analyze the settlement at the top and bottom of the tunnel,analysis the deformation of cross section,but also make the overlay analysis through the rule grid.The results of the superposition are compared with the results of the software Cloudcompare,and the results are basically the same.