Research On The Application Of3D Laser Scanning Technology In The Tunnel Deformation Monitoring

The traditional measurements have a good application in detecting building deformation, such as the ground-based measurement, the GPS technique and the Photogrammetry. But these technologies are still the kinds of point-to-point measurements. The monitoring coverage is limited, and these measurements are difficult to express the whole deformation information. But if we detect building deformation with the3D laser scanning technology, we can get the high density engineering data, and find out the whole deformation of buildings. This technology breaks through the traditional measurements. Therefore, the research of3D laser scanning technology has an important significance. At last, a method for detecting whole deformation based on3D laser scanning technology is proposed in this thesis.In this thesis, the data comes from the terrestrial point clouds. The above measurement includes five parts:the coordinate system unifying, data compression, tunnel sections cutting, computation of overbreak-underbreak, deformation analysis of tunnel. First, in the process of coordinate system unifying, we calculate the parameters with more points. Second, in the process of data compressing, the data reduction method based on octree coding is compared with traditional method. Then, we proved that the algorithm with hierarchical weight is more applied to tunnel. Third, in the process of tunnel sections cutting, in order to control the fitting precision of the center line, the constringent algorithm with slope and the robust method for fitting a plane to point clouds are used to cut tunnel sections. Through computing the area of tunnel sections, we detect the whole deformation by checking the area of tunnel sections and the difference of radiuses. At last, the traditional methods are improved for detecting the whole deformation.On the base of above research, the3D data processing and analysis system was developed. The main function of the system is data processing, such as the coordinate system unifying, data compression, tunnel sections cutting, computation of overbreak-underbreak, the3DS models showing and deformation analysis of tunnel sections. Then, we use the extant data to verify the correctness of the system. The convergent tendency of tunnel can be detected by the comparison of adjacent fitting diameter, the maximum error is10.23mm and the minimum one is5.57mm. According to the regulation, the tolerance is3mm, so this error is beyond the scope of tolerance. Therefore, the research of3d laser scanning technology still need more working. Furthermore, compared with the traditional methods, the3D laser scanning technology has an obvious advantage in respect of data size and data acquisition rate.