Automatic extraction method for transverse diameter of subway circular shield tunnel

Abstract

The invention belongs to the field of tunnel structure deformation detection, and relates to an automatic extraction method for the section diameter of shield tunnel three-dimensional laser scanning point cloud. The method at least comprises the steps of: 1) acquiring shield tunnel inner wall point cloud by using a three-dimensional laser scanner; 2) generating a tunnel inner wall grayscale imagemap by using the tunnel point cloud; 3) identifying waist seam positions on two sides of a ring piece ring by ring; 4) automatically extracting points which are 0.813m away from the lower parts of thewaist seams on the two sides as diameter extraction references; 5) calculating the transverse diameter of the ring piece ring by ring according to the diameter extraction reference point; and 6) automatically detecting the diameter extraction quality ring by ring, performing manual intervention correction on the diameter with poor quality, and correcting the position of the reference point. The method has the advantages that the diameter calculation reference point used in traditional total station measurement is automatically extracted from the point cloud, the section diameter extraction precision is improved, the problem that an ellipse fitting extraction algorithm commonly used in the prior art is low in precision is solved, and the method can be better fused with a total station measurement result.

Description

technical field [0001] The patent of the invention belongs to the field of deformation detection of tunnel structures, and is an automatic extraction method of cross-section diameter for three-dimensional laser scanning point clouds of subway shield tunnels. Background technique [0002] After the subway shield tunnel is completed, due to the impact of trains and external forces, the tunnel often deforms. In order to understand the amount of deformation, it is necessary to measure the subway tunnel regularly. At present, the commonly used measurement method is: pre-arrange the diameter measurement reference point at the chord length of 0.813m below the waist seam on both sides of a ring in the tunnel, and then use the total station to measure the prism-free coordinates of the diameter measurement reference point, and calculate the two The distance between the side reference points, as a measurement of the tunnel ring diameter. [0003] As the scale of underground rail trans...

AI Technical Summary

Problems solved by technology

However, for tunnel point cloud processing and extraction of tunnel diameter, there is no effective method. At present, the commonly used technical method is to slice and extract the point cloud of a certain ring, fit each ring point cloud to an ellipse, and extract the long axis of the ellipse as Current disc diameter measurement

However, it has been found through practical application that due to the difference in measurement methods and technical means, the segment diameter obtained by using the point cloud ellipse fitting method has a large gap compared with the diameter measurement results of the traditional total station, the data is difficult to integrate, and the external coincidence accuracy cannot be achieved. ensure

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