A Reasearch Based On Optical Fiber Ultrasonic Sensing For Bridge Settlement Distributed Detection And Analysis

With the development of the national economy level,there will be quantities of large-scale structure projects such as highway bridges,viaduct,high-speed railway bridge have been built in the coming decades.As an important part of the road,the security issues of bridge will also be widely recognized.Among them,the bridge settlement monitoring is critical for the safety and stability of the whole bridge.Since the limitation of the existing monitoring technologies for long-term settlement monitoring of bridge,it is of great practical value and economic significance to carry out the new type of long-term settlement monitoring and research.Firstly,this paper introduces the bridge settlement monitoring technology commonly used at home and abroad at the present stage.Through the comparative analysis of the advantages and limitations of these technologies,the difficulties of bridge settlement monitoring methods are summarized.It provides a reference for the research of bridge settlement monitoring technology in this paper.Through the research of the principle and applications of the ultrasonic and acoustic ranging,we conducted the detecting experiment and analyzed the advantages and limitations of the two methods.In this paper,a novel optic fiber sensor structure based on ultrasonic and acoustic ranging system for bridge settlement distributed monitoring is proposed for first time.Based on it,the measurement principle of the system,optimizing design of sensor,establishment of displacement sensor system and simulation analysis of bridge settlement is studied.The main research contents include:1.In this paper,the principle and the present situation of ultrasonic and acoustic ranging technology are investigated,through simulation and experiment,the structure of the sensor has been designed and optimized and it improves the sensitivity for ultrasonic and acoustic detection.Through the experimental scheme of ultrasonic ranging and acoustic ranging,the advantages and limitations of the two methods are analyzed.2.Through analysis of the theoretical basis of the combination of ultrasonic and acoustic and the ranging experiments of ultrasonic and acoustic,ultrasonic and acoustic ranging system is proposed,aimed at the use of large measurement range and high accuracy for displacement sensing monitoring,and the feasibility of the technology is verified by the displacement sensing experiment.3.The acoustic-ultrasonic distributed displacement sensing monitoring system is designed and constructed.The measurement accuracy of the system is measured in the process of displacement measurement.The error is kept within 10%,and the measuring range can reach more than 85mm.4.Through building the bridge settlement test system and the simulation of the bridge settlement regularity of each stages,the simulated settlement monitoring experiment has been carried out.Based on this,the feasibility and performance index for bridge settlement monitoring is verified,which provides a theoretical and experimental basis for the practical application of the system in bridge settlement monitoring.