Abstract: In order to make up for the shortcomings of traditional low-strain detection methods in identifying the integrity of high-cap pile foundation and the pile length information, a novel vertical uneccentric excitation method and an axial multi-point traveling wave decomposition of a series of velocity responses along the shaft pile are proposed in this study. Furthermore, two-dimensional and three-dimensional finite element models are used in this study to verify the feasibility of the method in identifying the integrity of high-cap pile foundation and pile length information. Finally, a series of influencing factors such as pile size, capsize, sensor setting locations, spacing, and other parameters are analyzed. The research results show that this method can eliminate the influence of the superstructure complex vibration characteristics and high-frequency noise after processing the initial complex speed response. Hence, a clear and identifiable response curve of the bottom reflection of the pile and effectively predicting the unknown pile length can be obtained. It can be concluded that this study can break through the limitations of the existing non-destructive testing methods and has reference significance for the integrity judgment of the existing high-cap pile foundation and the pile length prediction in actual engineering.

Key words: non-eccentric vertical excitation method, low-strain detection, axial multi-point traveling wave decomposition method