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| | Abstract | | In the maintenance of headrace tunnels, visual inspections of lining concrete are conducted during suspension of water supply, checking crack, scouring or junker. As to strength of lining concrete or state of natural ground, concrete coring at the point is the best way. But it is time consuming to core lining concrete at many survey points. Because of the limitation of suspending water supply, easier and more objective methods of evaluating the soundness of lining concrete are needed. In this study we examined the method of evaluating the soundness of lining concrete using GPR.GPR survey is a common survey for detecting the cavity at the back of lining or evaluating the thickness of lining. At the GPR survey at headrace tunnels, scattering waves thought of as scattered at the void in the deteriorated lining concrete are observed. We consider that scattered wave can be used for evaluating the soundness of lining concrete, calculating the RMS value of the scattered wave part. In this paper, we introduce about the soundness evaluation method using GPR and the application case to the headrace tunnel in service. |
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