Research On Pavement Health Monitoringsystem Based On Rayleigh Wave

With the deepening of China's modernization process,the scale of civil engineering construction is larger and larger,and its structure is more complex and diverse,such as urban rail traffic facilities,highways,large span bridges and high-rise buildings.At the same time,the safety accidents caused by structural damage often occur,and the damage of civil structure has become an important factor that threatens the safety of large buildings.Therefore,the damage detection of civil structure has become an important research topic in today's society.In this paper,a new monitoring scheme based on Rayleigh wave surface health monitoring system is designed for the non-destructive testing of pavement,which is a new solution for the non-destructive testing of pavement in view of the shortcomings of poor real-time detection,high cost and difficult operation of road surface testing equipment and method in civil structure.Based on the basic concept of Rayleigh wave,this paper introduces the wave equation,the formation process,the dispersion phenomenon and the field exploration method in Rayleigh wave,and improves it in the traditional frequency waviness transformation method to extract the Rayleigh wave frequency Scattered curve.By using the finite difference method to numerically solve the first-order velocity-stress elastic wave equation,the numerical simulation of Rayleigh wave in elastic medium and viscoelasticity medium is realized,and the snapshot of wave propagation in Rayleigh wave field is obtained,and the program is drawn by Matlab software Rayleigh wave propagation profile.The numerical simulation results show that the transient Rayleigh wave can propagate outward in the horizontal direction,but it is exponentially decay in the vertical direction.It provides the detection of the road surface defect by using the transient Rayleigh wave in practical application Theoretical basis.In order to verify the correctness of numerical simulation of finite difference method,this paper uses the dynamical module in ANSYS finite element software to simulate the wave field of transient Rayleigh wave in semi-infinite elastic medium,and obtain snapshots of the wave field coincided with the propagation of Rayleigh wave.Finally,a finite element model with underground voids is designed by ANSYS finite element software.The displacement data collected by nodes on the pavement are processed and analyzed by Matlab software,which is transformed into a file format which can be processed by using the improved frequency wavenumber.The method of data processing can be used to reflect the dispersion curve of the underground medium structure,and then the position of the underground void can be accurately judged according to the dispersion curve,which provides atheoretical basis and simulation basis for detecting the damage location of the road surface in the civil structure.Based on the numerical simulation and finite element simulation analysis of transient Rayleigh wave,a set of health monitoring system based on Rayleigh wave is designed based on wireless sensor network technology.And according to the monitoring object to develop the entire health monitoring system design,giving a detailed hardware and software design process.In the short-range wireless transmission scheme,several more commonly used wireless communication technologies are compared.Finally,the ZigBee technology is used to set up the wireless sensor network.The sensor nodes collect the Rayleigh wave data and transmit them into the computer monitoring system for processing.In order to verify the feasibility and effectiveness of the system,a transient Rayleigh wave was designed to test the non-destructive testing of cement concrete components with defects.Compared with the existing health monitoring system,the system has the advantages of economic utility,simple operation and real-time monitoring,as well as important social and economic application value.