Simulation Research On Multi-wave Propagation In Pile Dynamic Testing

At present pile integrity testing mainly adopts the method of reflected stress wave based on the theory of one-dimensional longitudinal wave. Though this method is quite applicable, the problem-solving ability is very limited and not as effective as socially expected. According to differences between the mechanism of wave propagation and the method of exciting, stress wave in the pile can be divided into the longitudinal wave, the torsional wave and the bending wave. The torsional wave and the bending wave are similar to the longitudinal wave in propagation characteristics, and they are even better than the longitudinal wave in many other aspects. With the 3D dynamic simulation research on the pile wave propagation in different loading methods, some new ideas about the pile integrity testing are put forward in this paper.Based on the stress wave theory, in this paper, the finite element analysis software COMSOL Multiphysics was used to do the 3D dynamic simulation analysis of the propagation characteristics of various stress waves produced in the process of right pile testing, with the precondition of making sure of the calculating precision and efficiency. Base on this, the dynamic responses at the top of the intact and the anomalous piles by different methods of impact was analyzed systematically, the suggestions about the receiving method of the longitudinal wave in the case of impact the solid and pipe pile eccentrically and vertically were proposed. In addition, proper loading and testing method was given when using torsional wave testing piles. For the testing signals influenced by a variety of factors in the process of propagation along the pile body. In this paper, the influence of different factors on the torsional wave in the process of pile integrity testing is deailedly analyzed and the axial and radial size and the position of the defect in the anomalous pile were discussed preliminarily. In the concluding part, a comprehensive analysis of the propagation characteristics in the pile were done and the differences between the longitudinal wave and the torsional wave. And it turns out that the proposals and conclusions given in this paper can be applied to engineering practice by making a comparison between the simulation results and the engineering example.