Multi-frequency Synthesis Method for the Simulation of GPR Electromagnetic Wave Propagation in Inhomogeneous Pavement Media
|Course||Road and Railway Engineering|
|Keywords||Inhomogeneous media Ground Penetrating Radar Propagation model Dielectric properties|
Ground Penetrating Radar (Ground Penetrating Radar, referred GPR) is a nondestructive detection instruments, underground target body detection using ultra-wideband electromagnetic pulse capable of detecting speed, continuous damage, high detection accuracy and low detection cost. Ground-penetrating radar for road detection, usually road material as a homogeneous material, Pavement Structure System model based on homogeneous assumptions to establish a uniform medium theory for data interpretation. The actual road material composition and structure has a non-homogeneous feature, road engineering materials are generally regarded as a mixture consisting of solid, liquid and gaseous phase medium component, showing the non-uniformity of the characteristics of the composition and structure of the media, different positions distribution of material dielectric properties are not the same. If you do not consider the non-uniformity of the material, using the theory of homogeneous medium for data interpretation, will not be faithfully and accurately reflect the inherent characteristics of the actual material. In this paper, the problems of above ground penetrating radar application technology to carry out ground-penetrating radar study of the propagation characteristics of electromagnetic waves in the pavement inhomogeneous media. The main contents and conclusions are as follows: (1) Based on the test, the dielectric constant of the road material (asphalt concrete, cement concrete), data analysis results show that the non-uniformity of the material of the actual road works is an objective reality. (2) based on the electromagnetic wave theory to analyze the nature of electromagnetic wave propagation in one-dimensional inhomogeneous media, and the reflected wave and transmission wave amplitude and propagation velocity. (3) The combination of the pavement structure system and road material characteristics the discrete structural layer of the pavement by the establishment of a one-dimensional non-uniform pavement equivalent structural model of the medium. The multi-frequency component synthesis method to simulate the propagation of electromagnetic waves in the pavement in inhomogeneous media, and the preparation of the corresponding program to achieve the radar electromagnetic wave propagation simulation. (4) The analysis and comparison of the simulation results of the radar electromagnetic wave propagation in homogeneous media and inhomogeneous media, the results show that better fitting considering medium simulation of the non-uniformity of the reflected wave and measured the reflected wave. Simulation study to carry out ground penetrating radar waves in the pavement in inhomogeneous media, to fully tap the the radar analog wave signal contains a wealth of material information, the result is more in line with the characteristics of engineering materials, thesis research can provide a theoretical interpretation of GPR data supported.