Benefits from using two receivers for interpretation of low-strain integrity tests on pipe piles

The double-velocity symmetrical superposition method (DVSSM), which consists of superimposing and averaging two synchronization signals measured at two symmetrical points of the neutral plane of flexural vibration (in an angle of 90 degrees), is proposed to eliminate the high-frequency interference at the pipe pile head without increasing the predominant period of impact pulse. An analytical solution is derived using the transfer matrix method. The calculated responses from the developed solution are compared with the experimental results for different receiving radius angles to evaluate the effectiveness of the developed solution. A parametric study is also conducted to investigate the suitability of the DVSSM. The findings demonstrate that the high-frequency interference is caused by a combination of the flexural behavior of the pile cross section and the wave propagation along the pipe pile head. The flexural vibration mode comprises the primary component of the high-frequency interference, which can be eliminated through the DVSSM without increasing the predominant period of impact pulse. The DVSSM can serve as an efficient method to detect defects near the pile head with much higher detection accuracy than the conventional method.