Inverse Analysis Of Dielectric Properties Of Layered Structures And The Applications In Engineering

Ground Penetrating Radar (GPR) is an effective, speedy, continuous and non-destructive testing technology using broad-spectrum electromagnetism technique for detecting the distribution of underground structures with low cost and high resolution. At present, GPR has been an important part of non-destructive testing (NDT) technology for layered structures such as road, runway, bridge, tunnel, dam, dike etc., and represents the developing direction of the testing technology for thickness, compaction, void content, moisture content and asphalt content etc. of structural layers. Lacking of precise forward model of GPR Electromagnetic (EM) wave propagation in layered structures, reasonable dielectric property model and the inverse analysis theory for layered structures, limits the development of GPR NDT technology, and results in the current GPR technology mostly relying on traditional experiential formulae and adjusting parameter manually. Most of the current achievements mainly focus on the measurement of structural layer thickness, and can only give the acceptable results for monolayered structure with lower absorption of electromagnetic energy. For the multilayered structures, the research is not very sufficient, and the accuracy is not yet satisfactory. The study on the other technical indicators for quality control (QC) such as compaction, void content, moisture content and asphalt content etc. is still under exploration.Inverse analysis of dielectric properties of layered structures and the applications in engineering are studied in this paper in order to solve the above problems of GPR applied technology. The main achievements and conclusions of this paper are summarized below:1. Aiming at the characteristics of layered structure and the complex dielectric properties of material, the forward model of GPR EM waveform propagation in layered structures, which considers the complex dielectric, is developed based on electromagnetic theory. Reflected GPR waveforms propagated in different layered structures are simulated using this forward model. This forward model has more extensive adaptability and evidently improves the calculation theory since the complex dielectric property of material is taken into account. It can be applied not only to the structures with lower absorption of electromagnetic energy but also to the structures with higher absorption of electromagnetic energy, and essentially overcome the limitation of current models which are only suitable for the material with lower absorption of electromagnetic energy, and therefore supply a religious theoretic model for the inverse analysis of dielectric properties of layered structures. The influences of the real part...