The estimation of the physical properties of subsurface objects using Cole-Cole equation
K. Kimura, H. Mikada and J. Takekawa
Event name: The 22nd International Symposium on Recent Advances in Exploration Geophysics (RAEG 2018)
Publication date: 24 May 2018
Info: Extended abstract, PDF ( 471.87Kb )
Ground Penetrating Rader (GPR) is a nondestructive testing method to visualize shallow subsurface using reflection of downgoing electromagnetic (EM) waves generated on the surface. The processing of GPR data has been developed using that of reflection seismology and the method is applied to survey wide area in an expeditious way, GPR has been widely used in many engineering fields. Quantitative analyses based on physical properties of buried targets have, however, not been well attempted in spite of increasing interest to the identification of subsurface materials in recent years. Since the combination of conductivity, permittivity, and magnetic permeability contrasts of material discontinuities causes the attenuation and the dispersion of electromagnetic waves that propagate through, reflected electromagnetic signals could be utilized to the material identification. In this study, we employed the Cole-Cole equation to analyze the attenuation and the dispersion of electromagnetic reflection signals for possible material identification using what are called the Cole parameters, i.e., physical properties. Since there are many materials for which the Cole parameters are not estimated, we employed a method using reflection signals for a two-layered earth model, that has a top layer of a material with the known Cole parameters and the second layer for which the Cole parameters are estimated. We use the dry soil as the second layer to estimate the physical properties using the Cole-Cole equation. Although we use very wide range of frequency in this study as well to discuss the optimum frequency band, we get good estimation result from thefrequency band from 107Hzto 108Hz, which is usually used in GPR.