The Asphalt Pavement Thickness Detection Technology By GPR Using The Antipodal Vivaldi Antenna Array

Since the asphalt pavement has sufficient mechanical strength,a certain degree of flexibility,plastic deformation and high damping properties,etc.,asphalt pavement has become the most commonly used form of highway pavement.Among the many factors that affect the life of the pavement,the thickness of the asphalt pavement is a very important factor,but also one of master projects in the construction process of quality control and acceptance testing projects,accurate information on the thickness of the surface layer are of great significance to the control of road quality,evaluation of structural performance and prediction of road life,however,the traditional detection method of asphalt pavement surface layer thickness-core drilling method has a huge limitation.GPR radar detection,because of its fast,accurate,non-destructive characteristics,can effectively compensate for the lack of core drilling method,so researching the GPR radar detection technology is very meaningful.Based on the theory of Vivaldi antenna and electromagnetic wave propagation,we use the GPR radar to detect the effect of the asphalt pavement layer thickness by the indoor simulated experiment.The main work and research results are as follows:(1)We in-depth analysis the basic law of electromagnetic wave propagation and the relationship between the electromagnetic wave propagation characteristics and permittivity.We introduce GPR radar system,working principle and performance.We summarize the current method for determining the electromagnetic wave propagation velocity inside the medium in the civil engineering and analyze their respective disadvantages of those methods.(2)We introduce the basic analysis methods of ultra-wideband antenna,antenna bandwidth broadening method and indicate the great performance of Vivaldi antenna.We compare the traditional Vivaldi antenna,antipodal Vivaldi antenna,balanced antipodal Vivaldi antenna and indicate that the antipodal Vivaldi antenna has good transmission performance and can be easily manufactured.(3)We introduces the basic design theory of Vivaldi antenna,design a antipodal Vivaldi antenna with the good performance by the large number of simulation,then manufacture it.We measure the performance of the antipodal Vivaldi antenna in the microwave unreflected chamber,then compare the measurement results with the simulation results.The results show that the measurement results meet our expectations and the requirements of GPR antennas.(4)We theoretically analyze the traditional common-source method and the improved common-source method and indicate that improved common-source method should have higher detection accuracy and faster detection speed.We simulate asphalt pavement using the succedaneous materials to do indoor simulation experiment with the antipodal Vivaldi antenna array by the improved common-source method.The experiment results meet our expectations and this method will have great significance for GPR in the pavement surface layer thickness detection applications in the future...