Three-dimensional finite element analysis on dynamic response of XCC pile in low strain integrity testing

A three dimensional finite element model was established to simulate the wave propagation in low strain integrity testing of X-section concrete pile (XCC pile). The velocity responses in time and frequency domains at different points on top of pile were obtained. By comparing the velocity responses at different points on top of pile, the high-frequency waves were analyzed, as well as the effects of pulse length, outside circle diameter and elastic modulus of pile on the arrival time and peak value of incident wave peaks. The results show that the velocity response on top of XCC pile in low strain integrity testing shows serious 3D effect, resulting in different arrival time of incident wave peaks at different points along bulge direction. The peak value of the incident waves close to pile center is the largest. The incident wave is negative after the first peak, while the negative response disappears when r>0.4R. The reflected waves from pile tip are almost the same. The high-frequency interference of XCC pile is different from solid circular piles. There are two kinds of interference frequencies on top of XCC pile. The arrival time of incident wave peaks and peak ratio of the incident and reflected waves are affected greatly by pulse length and outside circle diameter, but they are affected little by elastic modulus of pile. The influence of parameters is not obvious at r=0.4R in bulge direction on top of XCC pile. © 2016, Central South University of Technology. All right reserved.