臺灣博碩士論文加值系統

敲擊回音法在一般混凝土構造物非破壞檢測技術的實務應用上，檢測之裂縫深度多小於50cm，然此種檢測方式一旦遭遇到巨積混凝土之深裂縫時，由於使用之敲擊源較小（直徑3mm〜18mm鋼珠）產生之激發能源常感不足，導致接收到的訊號無法明確判讀，自然不易測出精確的裂縫深度。本論文研究之目的即針對巨積混凝土深度裂縫與深層鋼筋保護層厚度檢測時，恐有敲擊能量不足，訊號微弱之問題而提出訊號疊加技術以期能克服上述問題，達到精確檢測之目的。
本論文試驗之項目有1.裂縫深度達2.9m之巨積混凝土試體2.單根鋼筋保護層深度達9cm及3.束筋之鋼筋保護層深度達10cm，三組，經試驗結果顯示即使是敲擊源之能量不足時，應用訊號疊加技術在波形疊加5次至8次以後，測試之裂縫深度與實際裂縫深度均極相近，誤差率甚小，証明訊號疊加技術在日後鋼筋混凝土構造物之裂縫檢測之實務應用上有極佳之推廣潛力。

The application of the impact-echo method to detecting cracks with depths less than 0.5 m is satisfactory. For mass concrete structures, cracks may be much deeper than 1.0 m. The impact energy of normal steel spheres with diameters less than 18 mm is not enough to generate clear signals, which may result in significant measurement errors. The objective of this thesis is to develop a signal processing technique for deep crack measurement. The proposed technique makes use of superposition of signals obtained from repeated tests to enhance the signal amplitude of the wave arrival. It is expected to overcome the weak signal problem to increase the accuracy of deep crack measurement. In addition, the signal superposition technique is also applied to the measurement of cover thickness of reinforcing bars in concrete.
Experimental studies were carried out on a mass concrete specimen containing a simulated crack having a depth of 2.91m and on a concrete specimen containing reinforcing bars having cover depths of 0.09 and 0.10 m. Experimental results show that the signal, which is weak in a single test, is significantly increased after 5 times superposition of waveforms obtained from the repeated tests. The measurement results based on signal superposition are in good agreement with the known values. This demonstrates the feasibility of the proposed signal superposition technique.

第一章 緒論 1
第二章 文獻回顧及研究動機 5
2.1混凝土裂縫之成因與檢測技術 5
2.1.1 裂縫之成因 5
2.1.2 裂縫之檢測技術 7
2.2 鋼筋保護層厚度之檢測技術 16
2.2.1 磁電法 17
2.2.2 應力波折射法 19
2.3 研究動機 24
第三章 訊號重疊方法在深裂縫檢測上之應用 27
3.1 表面裂縫深度檢測之原理 27
3.2 可感測敲擊時間原點之裝置與檢測 29
3.3訊號重疊法在深裂縫檢測上之應用 31
3.3.1試體規劃與製作 32
3.3.2檢測結果分析與討論 33
第四章 訊號重疊方法在鋼筋保護層厚度檢測上之應用. 37
4.1 試體說明 37
4.2 試體波速量測 37
4.3 鋼筋保護層厚度之檢測試驗 39
4.3.1 單根#8鋼筋保護層厚度0.09m之檢測 40
4.3.2 二根#8束筋保護層厚度0.10m之檢測 42
第五章 結論與建議 45
5.1 結論 45
5.2 建議 46

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