Research On Defect Of Foundation Piles Based On Low Strain Reflected Wave Method

At present,Chinese engineering construction is constantly increasing.The pile foundation has the advantages of high strength,large load and wide application.The pile foundation belongs to the underground engineering often used in civil engineering construction.Therefore,It's easily to be influenced by construction methods and the surrounding environment.The results from this elements reducing the quality of the entire project and causing a crisis in the life and property of buildings and personnel.Therefore,it is necessary to make more research work to improve the integrity detection of piles.This paper are based on the theory of low-strain reflected wave,studying the distinguishing of pile defects through the outdoor model test and finite element numerical simulation.The main work and conclusions are as follows:(1)The analysis of detecting waveform through Pile foundation testing tests which are carried out by establishing complete piles,typical defective piles,two defective piles,three defective piles and a variable diameter pile model,verifies the stress wave propagation and reflection rule of the typical imperfect piles and summarizes the judgment methods of various imperfect piles and reducing piles.(2)On the basis of the test detection waveform,the software of the pile dynamic tester is used to analyzes perform digital filtering and wavelet filtering analysis on the original waveform,and summarize a filtering method approaching the theoretical waveform that can easily identify the defect type and position(3)Introduce the fractal theory to analyze and calculate the fractal dimension of the detection waveform of intact piles,one kind of defective piles,two kinds of defective piles and three kinds of defective piles,concluding that there is a correlation between the type of defect present in the pile and the fractal dimension of the detected waveform.(4)By using the ABAQUS finite element software to perform low-flux variation simulation of the test model,analyzing the numerical simulation results,verify the feasibility of the numerical simulation and the test results.