Research On Tunnel Sections Extraction Based On 3D Laser Scanning Point Cloud Data And Its Application

Tunnel engineering has broad applications in the constructions of national high-speed railway,high way,and urban railway system.Traditional methods such as laser profiler and total station with the stationary reflecting prism are widely used in construction survey,section survey and deformation monitoring.However,because these methods can only provide discrete distribution of section feature points,and they suffer from low efficiency and high cost issues,they can no longer meet up with the increased construction efficiency and precision requirement in modern tunnel construction projects.Point clouds data are acquired from 3D laser scanning.From these data points,one can extract the tunnel sections' fitting curve to measure,describe,and analyze the spatial information of tunnels in a highly precise and efficient way,both visually and numerically.Point clouds data processing mode can also be applied to three-dimensional reconstruction,tunnel section fitting,tunnel deformation monitoring and over-under-excavation analysis in tunnel constructions.In this research,we collected and analyzed point clouds data from actual tunnel construction sections of Changchun urban railway system.Here we propose a highly precise and efficient data acquisition method for data collection,process and analysis.We developed protocols of layout principles of tunnel control network,station planning,scanning process,and preprocessing of point clouds data methods(including point clouds registration,point clouds filter,reducing and so on).The above methods utilize Microsoft Visual Studio development platform,PCL(Point Cloud Library)point clouds processing C++ open source programming library,Geomagic Studioand Z+F Laser Control softwares.Next,we optimized the methods for tunnel sections surface fitting based on tunnel point clouds data,realized tunnel central axes extraction based on RANSAC,and realized tunnel transverse section extraction and the section curve fitting based on three times B spline fitting.Using Leica TS30 high precision total station to verified our measurements,we showed that our method is of high accuracy and efficiency,steady and reliable.On the basis of the theories and experiments above,we used Z+F IMAGER5010 C 3d laser scanner to get the actual point clouds data,and achieved the following applications: 1)Using newly built tunnel section of Changchun metro Line2(Jiefang Rd.to Pingyang St.passing under the existing metro Line1)as an example,we proved the engineering application in tunnel sections deformation monitoring.2)Using the actual project one construction section of Changchun light rail transit eastern extension line(Dongdaqiao Station to Puppet Manchurian Imperial Palace Station)as an example,we proved the engineering application in over-under-excavation analysis.