Study Of The Method For The Monitoring Of Railway Tunnel Vault Settlement Based On Terrestrial Laser Scanning

The railway tunnel vault settlement refers to the settlement of continuous half-circle vault based on the main arch structure of tunnel.In recent years,Chinese technology and economic development continue to promote the rapid construction of railway tunnels,railway lines increased year by year,the train running speed,which requires the railway tunnel vault settlement monitoring efficiency and quality should continue to improve.At present,there are a variety of tunnel vault settlement monitoring methods at home and abroad,but because of the limitations of these methods,they can not meet the current increasing demand for tunnel dome settlement monitoring.The data density is low,the acquisition speed is slow and the human consumption is large.The digital photogrammetry can obtain the digital image data processing process through image registration and orientation.The digital image data can be obtained by the combination of the total station and the reflection target.Tunneling three-dimensional data,but the method requires good lighting conditions,thus limiting the application of the method in the tunnel;sensor measurement by placing a displacement meter in the tunnel,convergence meter to measure the relative settlement of fixed points,but can only monitor a single Fixed point,can not analyze the settlement of the entire section,time-consuming and laborious;tunnel settlement detection vehicle can be real-time,fast access to equal spacing tunnel cross-section,but because of the cost of production in China,the number of production applications is not much.The three-dimensional laser scanning of the ground can obtain the point cloud of the measured object through the long-distance non-passive measurement method.It has the advantages of high speed,high precision,high density,no time limit and so on.This paper studies the method of monitoring the tunnel dome settlement based on the ground laser scanning point cloud data.The main contents of the study are as follows:The method of monitoring the tunnel dome based on the ground laser scanning point cloud data is as follows:1)This paper studies the principle of monitoring method of tunnel vault settlement,combined with the characteristics of 3D laser scanning data of the ground,and studies the method of combining the three-dimensional laser scanning data of the ground with the monitoring of the tunnel vault to sort out the railway tunnel arch based on the ground laser scanning Technology and framework for monitoring of top settlement.2)Combining the structure and characteristics of the tunnel,the study of the ground laser scanning point cloud for the boundary detection of railway tunnels Segment preprocessing method to study the rational design of the station,laying the target and the tunnel point cloud redundant information in the targeted filtering,thus streamlining the point cloud data to improve the data accuracy method;study based on panoramic images and point cloud From coarse to fine registration method.3)The method of calculating the settlement of the dome of single-station railway tunnel is proposed.First,Surface subsidence analysis,by establishing the coordinate system to extract the cross section,according to the point cloud slices to determine the elevation and settlement of the points;through the cubic spline interpolation method to deal with the discrete points on the cross-section to improve the discrete point density;Window median filter algorithm smooth curve;by asking the derivative of the curve to find the range of extreme points.Secondly,the single station dome settlement analysis is carried out based on single station dense cross section TIN.The discrete point set filter is realized by grid filter based on mathematical morphology,and the single station vault settlement analysis and visualization are realized by constructing TIN and filling.4)Verify the approach proposed in this paper by two experiments,and these experiments show that the monitoring method of railway tunnel vault settlement based on 3D terrestrial laser scanning is effective.