The Applied Research Of Pile Integrity Judgment With Acoustic Transmission Method

The integrity of the foundation pile nondestructive testing method has a lot of kinds, the common method has low strain gauge, high strain gauge, acoustic wave transmission method and drill sampling method. Among them, the low strain gauge and acoustic wave transmission method which with its advantage of high sensitivity, simplicity of operation, low cost are frequently used in concrete piles completeness inspection.As the very important means of the foundation pile completeness inspection, low strain method and the ultrasonic method still exist great limitations. Low strain method, will be affected by pile body length, pile diameter size, transient vibration intension, pile soil changes the influence of many factors, which causes signal distortion or defect position determine not accurate picture, can’t reached detection effect, and lose the actual meaning of detection. And in detecting process acoustic wave transmission method are easily affected by external factors, such as acoustic pipe, coupling agent. And even though the data from the test result is more abundant, the results of detection method of parameters for the defect of the criterion of precise location and determine the scope of different, which makes the inspection personnel vulnerable to subjective factors, to judge the results of detection problems.This article is based on a defects pile in the actual engineering, which discovered in the substructure of a aqueduct in the water conservancy project has discussed the determination of the accurate defects position and extent, the problems of study are as follows:1. For the ultrasonic wave transmission method detecting result of this defects pile which using different criterion analysis method obtains different suspicious defect position. At the same time, using low strain gauge ultrasonic transmission method to detecting out the external influence of acoustic pipe and coupling agent in acoustic wave transmission method;2. Introduction the ultrasonic wave fan scanning method, to the foundation pile suspicious defect position different depth of scanning judge;3. Excavation out the actual defects of the foundation pile, and measured the accurate defect position, concludes the real depth and the scope of defects. Do the test of comparison and analysis, comparing the results of the actual defects with the different judged results of the ultrasonic wave transmission method, simultaneously, analysis the results of this comparison and get the conclusion is that:The fan scanning method to decide the location of the exact defect in the foundation pile is exactly and its range is also feasible.4. As the only analysis method of the result detected by fan scanning method, the judgement of the actual measured wave method often rely on sound velocity and amplitude only. For this shortcomings, the author use the module of ANSYS Multiphisics/LS-DYNA to simulate the complete finite element simulation pile and get ideal waveform of the complete pile. At the same time, get the waveform by the finite element analysis in the ideal defects foundation pile, and contrast it with the waveform of the complete pile. For the waveform of the ideal defects foundation pile can solve the shortcoming which uses the sound velocity and band of the judgment only, judge method of the actual measured wave have the basis.