Detection sensitivity analysis of pipe pile defects during low-strain integrity testing

Abstract

The detection sensitivity of pipe pile defects during low-strain integrity testing is investigated with the consideration of soil plug, the soil sandwiched in neck defect and high-frequency interference at pile head. The additional mass model and fictitious ring-soil pile model (FRSPM) are introduced to simulate the soil plug effect and the dynamic interaction between the sandwiched soil and neck defect, respectively. The high-frequency interference is realized by considering the stress wave propagating both in the vertical and circumferential directions. An analytical solution for the dynamic velocity response of pipe pile is derived in the frequency domain through the transfer function method, and the corresponding semi-analytical solution in the time domain is then obtained by using the inverse Fourier transform. The reasonability and accuracy of the developed solution are verified by a series of field experiments. The dynamic interaction between the neck defect and the FRSPM is clarified via the parameter sensitivity analysis. The non-detection zone of pipe pile during low-strain integrity testing is analyzed. It is shown that the main factors to affect detection accuracy are the reduction degree and the location of defects, and there exists a location non-detection zone near the pipe pile toe.