Simulation Analysis Of Pile Integrity Test

With the development of economy, all kinds of high-rise buildings were quickly constructed in the city. The foundation part often occupies a great proportion in the investment of the whole of high-rise building. The fundamental part often adopts the pile foundation. The quality of the pile foundation engineering is directly related to the structure security of the building and people’s life and property security. Therefore, the quality detection is an important part in the process of pile foundation engineering.According to the pile foundation defect which is common in the engineering, such as expanding, necking and segregation defects, the corresponding finite element model of the defects pile is established with Abaqus/Explicit. The stress reflection wave curve change rule of the defective piles is studied when the defect length and position is changing. With the analysis of the waveform data, the signal characteristics and difference of different kinds of defect pile are got. Thus the defects of pile foundation can be judged correctly and effectively and integral judgments are given, which provides a support for engineering application.With the combination of theoretical analysis, numerical simulation and spot test, the spot test signals of the model pile and engineering pile, the numerical simulation signal of dynamic foundation pile are analyzed. the main technical points of the low strain are analyzed, including the choice of test instruments and vibration equipment, pile head treatment, test parameters, sensor installation and vibration operation. The analysis and judgment of the testing data are given in theory (determining the average wave velocity of pile, pile body defect position calculation, pile body completeness category judgment by statistics). Then through the specific low strain testing, the numerical simulation curve and measured curve are fitting and contrasted. Calculating the crest value time difference of the reflection wave and incident wave in the column bottom, if the numerical simulation curve and measured curve are basically the same, then the pile model, the parameters determination of piles and soil and the results of numerical simulation in this paper are correct.In this paper, the wavelet transform is applied to pile detection signal. Based on wavelet transform of dynamic signal, the noise of the measured signal is eliminated. Compared with the signal analysis methods of the traditional low strain reflected wave method, the results show that the analysis will help the right interpretation of foundation pile integrity. Numerical simulation and field test show that this method combined wavelet transform and Fourier analysis, which gets mutual improvement, can realize the separation and extraction of the weak reflection wave of the foundation pile shallow defects.