Research On 3D Laser Scanning Tunnel Operation And Maintenance Monitoring Technology

At present,Chinese society is facing severe problems:The large population base leads to overcrowding of buildings and transportation facilities on the ground,and the land area cannot meet the existing population living environment.With the rapid development of the country,we have turned our attention to underground space.Therefore,underground and underground projects such as subways,highways,railways,underground garages and underground safety exits are gradually increasing.These underground tunnel works will change with time,and the overall deformation will also be affected.Failure to do so may lead to serious accidents,which may directly affect our lives.However,at this stage,we use the tunnel monitoring method,which 1s mainly the total station servo method.This method has various limitations and restricts the detection of underground works such as tunnels.We urgently need to find a new measurement method to replace this method.Three-dimensional laser scanning technology can scan the tunnel surface quickly,automatically,with high density and high precision,which just makes up for the shortcomings of traditional monitoring methods.Therefore,this paper attempts to use three-dimensional laser scanners to monitor the deformation in tunnel operation and maintenance,mainly from the following three aspects:(1)The special semi-elliptical structure of the underground tunnel causes the 3D laser scanner to be affected by the laser reflection incident angle when acquiring the tunnel data,resulting in a large number of errors in the results of the different incident angles.In order to explore the optimal angle of incidence,this paper analyzes experimentally,acquires data at different angles of incidence,detects the best angle of incidence during the experiment through data analysis,and determines the scanning distance.(2)According to the special circumstances of the tunnel combined with the traditional common splicing program for analysis,to improve the point cloud target mosaic program.Combining the advantages of global splicing and dual splicing,the improvement of the scheme eliminates the accumulated errors between adjacent stations.The common control point is used at the head end of the segment to unify the coordinate system,and the control points are set at the end of the segment.Compare the accuracy.Through this experiment,it 1s verified whether the improved scheme achieves the purpose of improving accuracy.(3)According to the acquired tunnel point cloud data,the normal vector information of a large number of points is automatically combined,the direction of the tunnel's center axis is accurately calculated,and a reference cylindrical surface coaxial with the tunnel is established;then,the 3D point cloud is projected by the cylindrical projection method.Mapping to two-dimensional space,and finally based on the surface of the tunnel triangulation automatically intercept section profile.It is verified by experiments that this method is consistent with the accuracy of the data obtained by the total station.