| The Ground Penetrating Radar (GPR), which is an effective, speedy, continuous and non-destructive testing equipment, its application in pavement technical characteristics such as thickness, compaction, void content, moisture content and asphalt content etc., has been an active international subject since 1980s.Based on elementary principle of electromagnetic theory and system identification method, the backcafculation of composite dielectric property of pavement structures and its thickness, compaction, void content, moisture content and asphalt content etc, is studied in this paper. The main achievements and conclusions of this paper are summarized below:1. The forwarcl model of GPR electromagnetic wave propagation in typical flexible pavement system is presented based on Maxwell Equation in elementary electromagnetic theory. The influences of the real part and imaginary part of dielectric of actual pavement on reflected GPR waveform are analyzed, and relevant conclusions are gained2. Based on the analytical SIDTHK(System Identification for backcabulating Dielectric and ThicKness of pavement Structures) program, the program for backcalculating dielectric property and thickness of flexible pavement structures is developed, and the acciracy of thickness backcafculation results is improved3. The relationship between composite dielectric property of pavement structures and its volumetric concertrations is studied in this paper. Thus the idea of evaluating compaction, void content, moisture content and asphalt content etc. is raised, and the successful exploration on rapid detection of compaction and void content is made, also the method of backcafculating compaction and void content of asphalt pavement is derived, then the program for backcafculating compaction and void content of asphalt pavement is developed Meanwhile, the worthful attempt is made for backcafculating asphalt content, and the effectiveness of this method is proved from the contrast results. |
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