Research On Detection And Management Of Surface Cracks In Tunnel Lining Based On 3D Laser Scanning

Quantitative extraction of crack and other disease information has always been the goal of nondestructive testing.The determination of the crack length and maximum width plays an important role in the structural evaluation and risk assessment of buildings.In the process of tunnel construction and operation,the main means of crack detection of the structure are manual photographing and on-site recording.This method has low collection efficiency and poor data quality,and it is unable to obtain the key geometric information of cracks quantitatively.With the rapid increase needs of metro tunnel construction detection,operation and maintenance,tunnel structure diseases need economic,rapid and accurate technical detection means.3D laser scanning technology has been developed rapidly in recent years and has been applied to the quality management of civil engineering.With the development of construction automation,the process and organization mode of construction site management are in urgent need of reengineering and optimization.Therefore,3D laser scanning technology is used to study the detection of cracks on the lining surface of tunnels,and based on this,the corresponding process design of quality management of cracks and other disease information on the construction site is discussed.Quality management of tunnel crack based on 3D laser scanning technology includes crack collection,crack extraction.On this basis,the process and organization design of quality management of crack and other disease information in a construction project are discussed.In the aspect of the crack collection,the relationship between the collection scheme and the accuracy of crack detection is systematically studied,taking into account the accuracy and efficiency of data collection and combining with the analysis of point cloud information required for crack extraction.A scheme of point cloud collection and pretreatment is developed to meet the need for information extraction of cracks in tunnel lining.In terms of crack extraction,on the basis of surface fitting with LMS and RANSAC,the internal point cloud was removed and the cylindrical surface was expanded.Then,the main geometric information such as crack width and length was extracted by the improved Alpha Shapes based on Delaunay triangulations.In terms of management,the efficiency and benefit of crack detection for tunnel lining based on 3D laser scanning are preliminarily analyzed.In view of the massive fracture information,the system architecture for fracture information management of the engineering project department is preliminarily designed,and the management process and organizational structure design that guide the implementation of 3D laser scanning technology are carried out.Entropy theory and Arena simulation are used to evaluate the improvement of management efficiency quantitatively.Finally,the crack information in a section of Xiamen metro line 3 is analyzed as an engineering example.The results show that the method proposed in this paper can effectively extract the regular crack information in tunnel lining,the relative error of the two main geometric parameters of crack width and length is within 10%,and the crack with a width of more than 0.6mm can be detected.In terms of efficiency,the management organization design proposed in this paper can improve the efficiency of fracture information management in the project area by about 42% theoretically.