為提高樁長評估的效率和準確性，本文研究應用敲擊反應與地電阻影像兩種實驗方法，在三根長細比大於20模型混凝土樁，於架空與部分埋入條件下，進行敲擊反應先導試驗。根據導波理論將樁視為波導，利用相速度與頻率的頻散關係，建立聯合歷時與譜的分析，並在已知樁徑與波速的情況下，將共振概念與導波理論相結合，發展一套簡單而有效的方法，求出共振頻率、相速與樁長。 此外，經驗模式分解(EMD)技術用於確定下限頻率，其中兩個要求，即恆定速度與規律頻距，可滿足應用一維(1-D)波概念在高頻範圍。除下限頻率之外，一維波的概念被合理地根據頻率分析，用於預測樁長。 最後，實施基礎檢測策略以評估現地高架鐵路與跨水橋梁之樁柱式基礎長度。地電阻影像檢查揭示橋梁下部結構與周圍軟土在樁彎曲處的整體界面，符合橋梁設計圖表資料;採用互易原理的超震檢測則可精細地逆推算樁長。 ;In order to improve the efficiency and accuracy of pile length evaluation, two inpsection approaches, such as impact response and electrical resistivity tomography, are considered in this thesis. The pilot impact response tests are performed at three model concrete piles with slenderness ratios more than 20 under both traction-free conditions and partially-embedded conditions. Treating a pile as a waveguide, this pilot test develops an analysis basis on joint time history and spectrum by using the dispersion relation between phase velocity and frequency. The usage of resonance concept and guided wave theory is a simple and efficient approach to find the resonant frequency, phase velocity, and pile length when knowing a shaft diameter and wave velocity of the pile. Furthermore, the empirical mode decomposition (EMD) technique is used to determine the lower bound frequency, where two requirements, i.e., constant velocity and regular frequency span, can be fulfilled in order to apply the one-dimensional (1-D) wave concept at high frequencies. Beyond the lower bound frequency, the 1-D wave concept is reasonably used to predict the pile lengths with an estimated based on frequency analysis. Finally, the foundation inspection strategy is implemented to assess the pile bent lengths of the viaduct railway and the overwater bridges. the electrical resistivity tomography inspection reveals the global interface between the bridge′s substructure and the surrounding soft soils over pile bents, which is confirmed by the bridge design charts. The reciprocal theorem-based ultra-seismic inspection provides an inverse computation way for evaluating the pile bent length.
