Application Research On The Bridge Detection Technology Based On The Three-dimensional Laser Scanning

In the past twenty years,traffic transportation has been greatly developed.Bridge construction should be paid equal attention to construction and maintenance.There are quite a number of bridges missing design or construction data,especially for bridges crossing rivers or railways.It's very important to recovery missing data and evaluate current usage performance for bridges with incomplete data.Three-dimensional scanning is an emerging mapping and surveying technique.Comparing with traditional measuring technology,three-dimensional scanning has the characteristics of good real-time,large volume data,strong digital and interactivity.The application of three-dimensional laser scanning is promising,which has been applied to the survey of cross river,village and high-altitude bridge.However,there are few applications in bridge detection,especially for old bridges.Based on the principle and process of old bridge detection,three-dimensional scanning technology is adopted to measure spatial deformation and provide the model size,concrete strength and other key parameters for static load bridge detection experiment.This paper aims to propose a new,convenient and accurate method of bridges missing data,which will provide guidance for application of three-dimensional scanning technology on bridge detection.The research content of this paper is as follows:(1)Based on the large number of old bridges missing design data,some current detection methods of old bridges are summarized in this paper.The methods focus on recovery basic data by destructive,non-destructive measurements and static load testing process.Besides,the principle,classification,characteristics and data processing are introduced.(2)Three-dimensional scanning technology is high automation,measuring efficiency.But its error sources are more,especially from instrument structure.Errors of scanning instrument and data processing are analyzed.Comparison with traditional geodetic and surveying instruments is given to investigate the feasibility of three dimensional laser scanning to deformation detection.(3)Operation steps,data acquisition and processing of three-dimensional scanning are introduced in detail through the outside scanning test on the deflection of support beam.The results have been verified by displacement gauge and numerical calculation.The precision and application effect of three-dimensional scanning are evaluated as well.(4)On the basis of outside scanning experiment,the detection application process and advantages of three-dimensional scanning to old bridges missing data are summarized comprehensively.An actual bridge testing case is used to demonstrate the practical application of three-dimensional laser scanning.Studies show that three-dimensional scanning can be applied to deformation detection of old bridges missing data,including acquisition of accurate model geometry size,elastic modulus of bridge structure and deflection measurement.It's feasible to use this new scanning technology to old bridge detection under proper operation.The great interactivity and multi-point testing characteristic has great potential to realize automation measurement.Moreover,the high precision which reaches the accuracy of total station and level can provide guidance for accurate finite modeling and faster bridge detection.