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| | Abstract | | We should develop effective examining and diagnosing method for maintenance of waterpower dam passed more than 50 years after the completion. The authors conducted the case studies at real high aging dam sites using plural geophysical explorations (seismic, resistivity, electromagnetic wave, and acoustic tomography) in order to detect deteriorated part within abutment at left right bank of dam body and basement rocks under dam. We evaluated generally present geophysical exploration technology. 1) Seismic tomography is most effective method for exploring weathering layers at abutment. However, it is necessary to raise a water level in boreholes to a borehole opening and arrange survey points surround the target area. 2) All tomography methods are effective for detecting deteriorate zone of the number m scale in basement rock under dam body. 3) Both electromagnetic wave and acoustic attenuation tomography are effective for detecting caves of the number 10 cm scale between dam body and basement rock. |
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