Analysis And Research On Deformation Of Subway Tunnel Based On Vehicle Lidar

With the rapid development of the urban rail transportation industry,subway lines in major cities have gradually increased.Due to the characteristics of large subway passenger flow and long running time,the safety of subway tunnels is particularly important,and regular deformation detection of subway tunnels is required.Aiming at the characteristics of high labor cost,long detection period and low detection accuracy of the traditional manual detection method,a portable track detection vehicle is designed.Low and active.This paper introduces the track detection vehicle,and conducts research on the processing of the point cloud data of the subway tunnel scanned by the on-board laser radar and the analysis of the deformation of the subway tunnel.The details are as follows:Introduce the main components of the track detection car,including the car body and sensor part,data acquisition part and data processing part.The on-board sensors are lidar,inertial navigation system,2D laser displacement sensor and encoder.The sensors cooperate with each other to detect subway tunnels and tracks.The on-vehicle lidar selects the SICK LMS111 type pulsed lidar for non-contact detection of the subway tunnel,scans to obtain the two-dimensional coordinates of the point cloud data,and combines the information of the encoder and the inertial navigation system to obtain the third-dimensional coordinates.Pre-processing the point cloud data,a method based on statistical feature filtering algorithm,radius filtering algorithm and bilateral filtering algorithm is proposed.The filtering algorithm based on statistical features and the radius filtering algorithm are used in combination to filter the large-scale noise of the lidar scan data,and the bilateral filtering algorithm is used to smooth the small-scale noise.The cubic B-spline curve fitting algorithm is used to perform two-dimensional curve fitting on the cross section of the subway tunnel.In the Visual Studio 2015 environment,the PCL point cloud library is used to 3D model the obtained point cloud data to obtain specific information on the three-dimensional surface of the subway tunnel..Aiming at the research on the deformation analysis methods of subway tunnels,the overall deformation analysis method and the local deformation analysis method of subway tunnels are proposed respectively.Combining the fitting results of tunnel curves and curved surfaces,a local deformation analysis method based on the minimum distance projection method(Minimum Distance Projection,MDP)for two-dimensional cross-sections andthree-dimensional curved surfaces is proposed based on the local deformation analysis.On-site tunnel data detection was carried out on the 100-meter test line in the school.After comparison and verification with the actual situation,the selected deformation analysis method can effectively judge whether the tunnel is deformed or not and obtain the specific deformation variable size.