Extration Of Tunnel Deformation Information Based On 3D Laser Scanning Data

In recent years, with the rapid national development, the facilities such as tunnel and subway are gradually increased. Facing the long running time and growing traffic of railway, highway, subway, if the safety problem of tunnel and subway doesn’t draw enough attention, lives and property would be threated. It is necessary to study the safety monitoring of tunnel and subway. Compared with the traditional tunnel deformation methods with long period, a lot of manpower and material resources and small amounts of data, a massive point cloud data with high density and precision can be obtained by three-dimensional laser scanning technology with scanning the tunnel surface fast and automatically.In this thesis, the processing and analysis based on the point cloud data and the analysis on tunnel deformation are mainly done in the following aspects:1) In the domesticating process of the cloud data coordinate systems in different periods, there are only errors of the control points coordinates in a single coordinate system taken into account with the least square method when calculating coordinate transformation parameters. And there are errors of the control points coordinates in two coordinate systems taken into account with recursive total least squares method during the process. It improves the accuracy of the transformation parameters, and reduces the loss of the precision in process of the domestication.2) The spatial position information of the tunnel is known before intercepting the section, so that the direction of the interception section is orthogonal to the direction of the tunnel. In this thesis, with the projection of the point cloud data on XO Y plane and XOZ plane, the central line of the tunnel are projected on both two planes by fitting the boundary curve respectively.3) Slice type of sections, which are fitted as circular and elliptic curves, intercepted with 1 meters interval, and the radius of the circle and the major and minor axis of the ellipse are used to measure the spatial deformation of the tunnel. Based on the tunnel point cloud data in two periods, the changes of the radius and the major and minor axis in the same section are compared in the amount of time.4) The cubic B spline curves is used to fit the outline of the tunnel section, and the changes of outline between two periods are compared so that the deformation of the tunnel is analyzed qualitatively. So minimum distance projection algorithm is used to calculate the deformation of each point on the section, that the local deformation information is extracted.