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| | Abstract | | Detection and evaluation of cracks that occur along the joints and lift surfaces of concrete are one of the important inspection items in the maintenance management of the concrete dams that have passed long after construction. To develop a new inspection technology which can complement existing technologies such as visual inspection and ultrasonic methods and inspect the large concrete dam more effectively, we are studying on an inspection technique using attenuations in addition to travel times of elastic waves. Last year, we conducted test measurements in a real concrete dam. In this test, the cracks confirmed on a part of the lift surface of the dam body were used as the main inspection objects, and elastic waves with a dominant frequency of about 1 KHz were transmitted and received using the top, slope, and inspection gallery of the dam. As one of the tests, surface waves were propagated along a measuring line crossing the crack, and their attenuations were measured and analyzed to estimate the crack depth. The test showed that the estimated depth was almost identical to the depth confirmed by coring. |
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