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| | Abstract | | Ministry of Land, Infrastructure and Transport is carrying out the overhaul for river management facilities of the whole country as one of the deteriorated infrastructure measures now. In the eastern Japan, it is also concerned that the potential damage attacked by the 2011 off the Pacific coast of Tohoku Earthquake is still remaining behind river structures. Therefore, the detections of the damages by using GPR exploration as a representative nondestructive inspection are important. The authors studied about the basics of GPR exploration by field experiment, numerical computation and so on, for the purpose of voids detection behind the river concrete structures. In concrete blocks for shore protection, we conducted GPR survey at the area of 19.6m by 3.5m. After we corrected irregularity of surface on GPR profiles, we analyzed void thickness and evaluated the soundness of the structure by calculating horizontal distribution of void thickness. In a trough pipe, we conducted an experiment of GPR data acquisition under the condition of 15cm water depth at a test tank. We evaluated the possibility of void detection under the water. These results showed that GPR survey was effective for an operation and maintenance of river structures. |
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