Method for extracting cross sections of radian tunnels on basis of land-based LiDAR (light detection and ranging)

Abstract

The invention discloses a method for extracting cross sections of radian tunnels on the basis of land-based LiDAR (light detection and ranging), and belongs to the technical field of civil engineering. The method includes intercepting point cloud data of the same cross section in different periods for monitoring deformation of tunnels and analyzing the deformation; establishing corresponding relations of points between deformation point cloud and reference point cloud, namely non-deformation point cloud, and computing deformation of the integral cross sections by the aid of minimum-distance projection algorithms; applying bidirectional projection processes, RANSAC (random sample consensus) algorithms and least square processes to extracting radian central axes pertinently for the radian tunnels; verifying the precision of ultimately extracted deformation of the cross sections and measurement results of total-station instruments. The method has the advantages that the quantity of the point cloud can be increased if the tunnels are long, rotation is only useful for to-be-extracted cross sections and the adjacent point cloud and is equivalently useless for the point cloud at other locations, rotation is carried out whenever each cross section is extracted for the radian tunnels, the concept of point buffer areas is proposed, only the point cloud adjacent to the extracted cross sections rotates, and accordingly the tunnel deformation computation efficiency can be greatly improved.

Description

technical field [0001] The invention belongs to the technical field of civil engineering, and relates to a method for extracting arc tunnel sections based on land-based LiDAR. Background technique [0002] With the development of the subway tunnel business, a large number of geologically complex and difficult mountain tunnels and urban subways are in full swing. During the construction period, the geological conditions are complex and the mechanical behavior of the rock-soil medium is constantly changing, resulting in complex and diverse tunnel construction. High, in order to ensure the stability of the surrounding rock and the reliability of the supporting structure, deformation monitoring is an indispensable key link in the construction of subway tunnels. Timely and accurate deformation monitoring of subway tunnels will undoubtedly affect the construction quality and overall safety factor. has improved significantly. The responsibility of deformation monitoring lies in th...

AI Technical Summary

Problems solved by technology

Although the classic least squares method in the model parameter estimation method can estimate and optimize the model parameters according to a given objective equation to make it most suitable for all given data sets, this method does not include detection and exclusion The methods for abnormal data, they are all based on the smooth assumption: regardless of the size of the given data set, there are always enough accurate data values ​​​​to eliminate the influence of abnormal data

However, in many practical situations, such as the tunnel wall is not smooth or affected by air humidity, there is a lot of noise in the tunnel boundary point cloud after projection, so the smooth assumption cannot be established, and the data may contain serious error data that cannot be compensated. When such model parameter estimation methods will not be available

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