Application Research Of Mobile 3D Laser Scanning Technology In Deformation Monitoring Of Subway Tunnels

With the rapid development of urban subway rail transit,it is accompanied by the urgent need for structural deformation monitoring of subway tunnels.The emergence of 3D laser scanning technology,especially mobile 3D laser scanner,with its high precision,fast,non-contact and many other advantages,the rapid improvement of subway tunnel deformation monitoring efficiency is close at hand,but at present,mobile 3D laser Scanning technology is very scarce in the research of subway tunnel deformation monitoring.There is no work flow that can be referenced,and the key technology of data processing is different from ground static station type 3D laser scanning technology.Based on the above-mentioned reality,this paper focuses on the application of mobile 3D laser scanning technology in the deformation monitoring of subway tunnels,and carried out the following research work:(1)Focus on the mobile 3D laser scanning system-Leica SiTrack one laser scanning system,and compare the advantages of 3D laser scanning technology in tunnel deformation monitoring by comparing with other tunnel deformation monitoring methods.(2)Referring to the operation flow of the ground static station type 3D laser scanning technology,the mobile 3D laser scanning data acquisition mode is explored,including the layout scheme of the target ball,the moving speed of the track trolley and the complete data collection process.(3)Research on key technologies of mobile 3D laser scanning point cloud data processing.Specifically,it includes pre-processing techniques such as point cloud denoising,point cloud reduction,target fitting,and post-processing techniques such as mileage correction,structural midline extraction,and cross-section extraction.The improved RANSAC algorithm based on tunnel elliptic parameter model is proposed.A three-dimensional laser scanning data acquisition process error source,designed a total station laser scanner dual-purpose prism target combination device to reduce data acquisition errors.(4)Taking the Guangji South Road Station-Yangyu Lane Station of Suzhou Metro Line 1 as the engineering research object,using the Leica SiTrack one mobile 3D laser scanning system to collect the 3D point cloud data of the tunnel,and use the relevant supporting software for data processing.The tunnel cross-section convergence analysis and ellipticity analysis method are used to obtain the deformation information of the subway tunnel.The error in the calculation of the control point meets the technical requirements of the Technical Specifications for Urban Rail Transit Engineering Monitoring.It is a mobile 3D laser scanning technology in the field of structural deformation monitoring of subway tunnels.The application provides a certain reference value.