Application Research Of Structure Inspection And Monitoring Based On 3D Laser Scanning

Major civil engineering structures such as long-span bridges,super high-rise buildings,large water conservancy projects and other infrastructure structures are the material basis to ensure the sustainable development of China's economy.The health and safety performance of these structures is an important guarantee for the safety of life and property of the people of our country.Therefore,how to conduct rapid detection and long-term monitoring of large structures in service has always been a research hotspot worldwide.3D Laser Scanning,an emerging surveying and mapping technology after GPS technology,offers an althernative way to acquire three-dimensional spatial data and information.As a new non-contact measurement method,3D scanning technology has the unique advantages of high efficiency,fast measurement speed,high measurement accuracy and high degree of digitization compared with the traditional measurement technology.It can realize the measurement without setting the reflection prism in the dangerous environment that is difficult for technicians to reach.It is the most advanced method in the modern measurement industry.By storing the spatial coordinates and surface information of the target objects in a high-density data grid,the measured objects can be described in more detail.Therefore3 D laser scanning technology provides great potential to smart inspection and monitoring of civil infrastructues and has received increasing attention in research and industry field.In this paper,the research background and status quo of structural inspection and monitoring technology at home and abroad and the application research status of 3D laser scanning technology in structural inspection and monitoring are systematically described.On this basis,this paper introduces the working principle and characteristics of 3D laser scanning technology,and studies the processing method of point cloud data.The main innovations and research contents of this paper are as follows:(1)In this paper,3D laser scanning technology is explored to be appliedon civil infrastructures among the whole life cycle.In the structural construction monitoring,this paper proposes an accurate 6-DOF pose measurement method for precast structure members,guiding effective erection to as-designed positions.The method incorporates rotation-discriminating correlation-based template matching for registering the incomplete scan data and the asdesigned structure as well as principal component analysis-based plane segmentation for pier pose estimation.The ultimate goal of this research is to assist the accurate assembly of the structure by measuring the spatial attitude of the components during the lifting process.(2)Aiming at the deformation measurement of existing structures,this paper presents a3 D deformation measurement method based on target center fitting.Considering that the fitted centroid of a reflector region from the scanned point cloud offers more accurate 3D information than a single point coordinate,a reflector-based center fitting method is proposed for displacement monitoring.The method is based on the principle of least square circle fitting(Pratt method),by fitting the boundary contour circle,and then obtain the center threedimensional coordinate of the target to measure the structural deformation.The method was validated in two load tests in laboratory of an assembly frame structure and an arch bridge model.The measurement accuracy and feasibility of this method can evaluated by the data from total station and LVDTs.(3)Aiming at the rapid measurement of the geometric shape of existing structures,a method of structural geometry shape detection based on edge detection algorithm is proposed in this paper.This method extracts the edge contour of structures through alpha-shape algorithm,and calculates its central axis after fitting the edge line into a smooth curve by the least square method.In this paper,the arch rib alignment is quickly obtained by using this method in an arch bridge model and an actual bridge inspection,which effectively verifies that the structure shape can be quickly detected by this method in practical engineering.(4)For the existing structure,especially the old structure without drawings,this paper uses3 D laser scanning technology to quickly obtain the 3D point cloud model of the structure,and then obtain the 3D grid model,which makes a prerequisite study for the subsequent applications like integrating with BIM models and importing for finite element analysis.In this paper,the Poisson surface reconstruction algorithm was used to reconstruct the 3D point cloud model of the structure obtained by scanning into a real 3D mesh model,and directly imported the model into the finite element software ABAQUS to realize the modal analysis of the structure by finite element software.Based on the above research,3D laser scanning technology indicates great potential in smart structural inspection and health monitoring fields,which provides useful datain the whole life cycle.It offers more important practical significance for structural construction,regular inspection and maintenance.