| This paper analyzes the low-strain dynamic method pile measurement data by wavelet analysis and other methods,discusses the problem of insufficient resolution of traditional digital filtering and exponential amplification methods in data analysis,and the influencing factors of stress wave propagation in the pile body.The application of new methods such as wavelet transform and fractal theory is illustrated by establishing a three-dimensional finite element solid model for simulation experiments,laboratory model pile experiments and field pile type actual measurement experiments.The main achievements and innovations of this paper are as follows:(1)The dynamic response of the foundation pile is simulated by the finite element method,and the model of the stress wave propagation process of the foundation pile under ideal conditions is obtained,and the numerical simulation curve that is more consistent with the theoretical curve is calculated.,to analyze the propagation process and reflection characteristics of stress waves in different pile bodies;(2)According to the finite element simulation and measured data analysis,the problems and shortcomings of the current low-strain reflected wave method for measuring piles are proposed.Different data processing methods are used to compare and analyze the results.Noise interference is added to the digital analog signal,and wavelet analysis is proposed.The data processing ability is better than the traditional method of digital filtering and exponential amplification;(3)Discuss how to choose the optimal wavelet base when processing data by wavelet analysis.Comparing the properties of the commonly used wavelet bases,Db N series wavelets have strong localization ability in both time-frequency domains in the process of signal decomposition due to their advantages of tight support and limited width.Db5 wavelet is selected to analyze and process the simulated and measured signals in this paper;(4)The new method of fractal theory is innovatively combined with the integrity judgment of foundation piles,and the box-counting dimension is introduced,which is not sensitive to noise,but the curvature and density of the curve can be well characterized by the fractal dimension.By comparing the fractal dimension of the intact pile type and piles with different numbers of defects,it is concluded that the change of the corresponding fractal dimension has a positive correlation with the number of defects in the pile body;(5)Analyze and compare typical measured signals,and through the comparison of different processing methods,it shows that the resolving power of wavelet analysis is stronger than that of digital filtering and exponential amplification.This paper aims to deeply study the comparison between low-strain detection theory and practice,combine emerging data processing methods,use wavelet analysis to improve the analysis accuracy of dynamic load detection data,and combine novel methods such as fractal theory into the field of dynamic load detection data analysis.The problem of quality judgment of foundation piles is analyzed from an angle. |
