| 講演要旨(和文) | | 建設から年限を経たコンクリートダムの維持管理上，コンクリートの継ぎ目やリフト面に沿って発生する亀裂の検知・評価は重要な検査項目の１つである．筆者達は，目視点検や検査範囲の限られる超音波法等を補完し，大規模なダムにおいても効果的に検査が可能な新しい手法の開発を目的に，弾性波の走時だけでなく振幅減衰も利用した検知手法の研究開発を行っている．昨年度，実際のコンクリートダムにおいて試験的な測定・解析を行った．この試験では，堤体のリフト面の一部に確認されている亀裂を主な探査対象に，天端，法面，監査廊等を利用して卓越周波数1KHz前後の弾性波の発受振を行い，亀裂の検知性能を評価した．試験項目の１つとして，亀裂を横断する測線にて，表面波の伝播試験を行い，その振幅減衰特性から亀裂の深さの推定を行った．その結果，別途コアリングにより確認されている深さとほぼ一致する結果を得た． |
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| | 講演要旨(英文) | | 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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