抄録
Detection and evaluation of contaminated soil and ground water by GPR method was discussed. The electric properties of soil and contaminant and their mixed material are significant for GPR. Some models for mixed material including CRIM model were discussed. As an example, CRIM model was compared with the measured parameters using sampled core, and showed good agreement under low water content condition. Generally, if soil is contaminated by hydrocarbon contaminant such as DNAPL and LNAPL, the contaminant will replace the water in soil. Consequently, the conductivity of the soil will decrease, and the dielectric constant of the soil will also decrease. We think GPR detect the change of the dielectric constant of the soil and can detect the anomaly caused by the contamination. However, we should note that if there is chemical or bio-chemical reaction related to the contamination, the phenomena will be much more complex. Then we showed some examples of GPR profiles, which were applied to soil contamination and ground water problems. We showed that the change of ground water table by 5cm can be detected by GPR, which means GPR has a good possibility for detecting small anomaly due to contamination, if the phenomena happen in a short period, or if we can measure the time-lapse data. When the contamination is steady state, we can use the combination of profile and CMP measurements by GPR. CMP measurement will provide good information about the material that causes reflection in profile GPR measurement.
