Ultrasonic Frequency Spectrum Analysis And Judgement For Pile Defect

With vigorous development of construction industry in our country, pile foundation hasbecoming a kind of importance foundation forms. But some kind of defects such ascontraction,separation,break are usually found in bored cast-in-place piles，which maybereduce bearing value of pile and do harm to the superstructrue,furthermore,make pile losecarrying capacity. Acoustic transmission method is a pile testing method through thepropagating process’s change of acoustic parameters and the waveform by ultrasound use inconcrete, inference and characterize the defective position,scope,degree and the mechanicalproperties of the pile body.First of all, make a comprehensively discusses about the most common method of piledetection, sorting and reviewing the theory of ultrasonic transmission method and thejudgment method and principle of the pile body concrete’s defects and introduced the basicknowledge of processing detection signal.Secondly，the simulation experiment of concrete defects in indoor is according to theexisting problems that judge the foundation pile integrity and defects types by conventionalpile foundation inspection methods,analyzes the different defects of concrete how to influenceeach acoustic parameters of ultrasonic and introducing the theory of ultrasonic spectrumanalysis,ultrasonic signal is transform time domain analysis into frequency domain analysis isrealized and the relationship between spectrum characteristic and different defects types isestablished, it make a effectively supplement for the foundation pile concrete quality judgemethod.Finally, analysis a engineering example by spectrum analysis method and validation byCore-Drilling, The conclusion shows that this method is more accurate and reliable than thecommonly used Probability Method.We can use spectrum analysis method to evaluate theProcessing results and master the result when deal with a defect pile.