Nondestructive Evaluation Of Pavement Structure Condition Based On 3D Ground Penetrating Radar And Falling Weight Deflectometer

At present,China has completed the construction of 140,000 kilometers of expressways.Asphalt pavement is an important type of expressway pavement,and its pavement maintenance has gradually become a urgent issue.The formulation of asphalt pavement maintenance programs usually requires a comprehensive understanding of the overall condition of the pavement.It can be said that the assessment of pavement structural damage and strength conditions is the key and important prerequisite for carrying out asphalt pavement maintenance.The traditional road detection technology usually only pays attention to the indicators of the pavement surface,and the assessment method for the internal condition of the pavement is relatively single,and the depth and breadth of the evaluation are limited,resulting in a low reliability of the evaluation results.In this paper,3D-GPR and FWD are used to comprehensively evaluate the damage and strength of the pavement structure.At the same time,the 3D-GPR is used to detect the thickness distribution and water accumulation of the pavement structure.Accordingly,the input parameters in the modulus-backcalculation system were optimized,and the load-bearing capacity of the pavement structure was accurately obtained.At the same time,combined with the parameters of the pavement surface conditions and the pavement structure parameters obtained by the 3D-GPR and FWD,a pavement quality treatment strategy is formed.The first chapter mainly introduced the development history of 3D-GPR and FWD and the research status at home and abroad.The second chapter focuses on the basic theory of internal pavement detection using 3D-GPR.The dielectric characteristics of the pavement material and the propagation characteristics of electromagnetic waves at the interface of two different media are analyzed.The principle of thickness detection of 3D-GPR and the principle of detection of internal damage on pavement.And the second chapter introduced the basic composition and detection principle of the FWD instrument.At the same time,the back-calculation method of the modulus based on the fitting accuracy of the deflection basin is described.The third chapter introduced the reliability of the modulus-backcalculation method was analyzed from the angles of deflection basin fitting method,temperature,load and time period based on the full-scale pavement test loop.It was confirmed that the modulus-backcalculation method has a good correlation with pavement material properties and has a high modulus-backcalculation accuracy.At the same time,the method of optimizing the modulus-backcalculation system based on the internal detection results of 3D-GPR is described.The fourth chapter introduced the background,technical status,and traffic status of the supporting project.At the same time,it analyzes the maintenance effects of conventional maintenance programs and points out the defects of conventional maintenance programs.At the same time,the 3D-GPR was used to detect the thickness and damage of the various structural layers of the pavement,and the most important types of diseases inside the pavement were obtained.And the fourth chapter introduced the results of deflection,and adjusts the parameters such as the thickness of the structural layer,the range of the backcalculation of the modulus,and the Poisson’s ratio in the modulus-backcalculation system based on the internal detection results of the pavement obtained from the 3D-GPR.Accurately obtained the strength of each structural layer of the pavement and the load-bearing capacity of the pavement structure.In chapter five,combined with the detection results of 3D-GPR and FWD,a quality treatment strategy for pavement was formed.