Numerical Research Of Wharf Pile Foundation Non-Destructive Test Method Based On 3D Guided-Wave Theory

As the base of wharf superstructure, wharf piles foundation is the key of the secure of wharf .The defects of piles ,such as broken,necked,expanded diameter etc, can be caused because the adverse impact of many factors. So it is a important work of NDT(nondestuctive testing ) of wharf pile.But the NDT of wharf pile is more complicate than that of single pile whose top free. Especially the NDT of wharf piles whose top foxed by wharf superstructure is most difficult because the heavy disturb of superstructure. Based on above reasons, it is a difficult problem in the field of detection across the world.In the paper, wharf piles are classified into three types: piles whose top free, piles whose top foxed by the wharf superstructure,and piles whose top pressed by wharf superstructure.At the Base of 3D guided wave theory, pile dynamic test technology, wavelet analysis and FEM Simulation Analysis, combing with test on site, a series of research work have been carried out on the NDT of wharf pile. The main contents and conclusions are as follows:1 The finite element modles of deffrent wharf piles considered beam and slab are set up.And the longitudinal wave test of wharf piles are simulated and researched, then some results are obtained: the NDT law of piles whose top free can be used to the NDT of piles whose top free of wharf and piles whose top pressed by wharf superstructure when they meet ? / R≥10; But the NDT wave of wharf piles whose top foxed by the superstructure is most complicated.2 A new method of longitudinal wave test of wharf piles is proposed. Moreover, it's shown that the simulated curves are in good agreement with those obtained from field measurements. Consequently, the numerical simulation and the method of wharf Pile test are correct and they will play an important role in increasing the accuracy of wharf Pile NDT.3 The torsional wave test of wharf piles are simulated and studied firstly. it is discovered that the superstructure disturb can be avoided effectively by the torsional wave test, and pile integrity can judged out. but the stress wave attenuate fast because the disturb of soil around pile.4 under the same structure parameters, the advantages and disadvantages are pointed out through the comparison of the waveform,wave velocity,attenuation rate,loading way,defect sensitivity and test accuracy of longitudinal wave test and torsional wave test of wharf piles. Moreover, it puts forward the synthesis analysis of longitudinal wave and tensional wave of wharf piles nondestructive test. Finally, it's shown that the simulated curves are in good agreement with those obtained from field measurements.5 the 3D effect of the wharf piles stress wave are studied from several aspects. it puts forward the 3D effect are always appear from the disturb of superstructure and the bigger pile diameter is, the distincter the 3D effect is. On the contrary, it is help to decrease the 3D effect through the load frequency reduced and sign received from different location.6 Through the analysis of original signal of wharf piles NDT, it has been found : the frequency analysis can get a better effect to the NDT of wharf piles whose top free or pressed by superstructure than those whose top foxed by superstructure. Firstly, the original sign of piles whose top foxed will be processed with the method of wharf piles NDT which proposed in the paper , then the filtered sign can be analysised in the frequency domain in the light of wharf piles whose top free.In conclusion, the NDT of wharf piles will be carried out mainly by longitudinal wave test ,combined with torsional wave test, assisted by frequency analysis.