| The anchor is the core components using in supporting infrastructure,which was buried underground.Relying on the surrounding rock interaction to secure infrastructure.As a result,the quality of the anchor directly influences its support of the stability of the engineering.And the quality of the anchor under geological factors,the influence of various factors such as the weather changing.Corrosion often occurs in surface or cross section,the anchor of security operation exist for a long time,most engineering accident is caused by corrosion of anchor.And some deficiencies of present detection anchor means,sometimes emphasize the real-time and ignores the durability of the anchor rod and sampling inspection can not fundamentally solve the problem,in general the use of traditional detection methods can not achieve the overall consideration.Other NDT(Non Destructive Testing)methods about anchor there are all kinds of defects.So,this paper proposed a method to detect bolt quality based on acoustic emission technique,the method is a new kind of simple and highly effective detection means,and the Acoustic Emission technique in bolt corrosion test for the first time,so as this paper main research direction.This paper main research content is divided into the following steps:1)Using on the basis of the classical mechanics and mechanics of elasticity is deduced respectively the wave theory of anchor in a state of freedom and in the vibration of the anchorage state law,but also in the external transient excitation is deduced under the incentive of anchor rod production and propagation law of stress wave,these are for the production of acoustic emission sensor provides a theoretical basis and parameters.2)Introducing the content of the Acoustic Emission technology,including Acoustic Emission detection principle,signal types and the signal analysis methods.And analysis of stress wave in anchor bolt end anchoring a free state,the namely at the interface between two different media propagation characteristics.3)According to the results of the analysis of the previous chapter,through some of the features of acoustic emission signal of anchor such as frequency,bandwidth,noise,etc.,using a kind of organic PVDF piezoelectric material as the main switch components,and designed a triple pre-amplifier circuit,trap circuit and power supply circuit,made a kind of applicable to this topic of bolt corrosion detection of ae sensor.4)Signal processing,first elaborated the basic principle of various methods,according to the characteristics of signals collected in this project,decided to adopt the time-frequency analysis method to deal with the experimental data.Anchor bolt in the experimental stage,the three test sample data collected by short-time Fourier transform and S transform respectively,got the time-frequency diagram,based on the analysis of two kinds of method after processing the results of the signal characteristics of the anchor test sample is obtained.5)And then in a certain field experiment on the scene of the serving of the anchor rod using the same method to collect the anchor of the signal,after dealing with the same,found at the scene of the lab to get the characteristics of signal and the anchor of extremely similar signal characteristics,these characteristics can be used to describe the quality of the anchor,verified the feasibility of acoustic emission technique in this field.This paper’s innovation lies in for the first application of Acoustic Emission technique in the field of the bolt corrosion testing,comparative study and found that the Acoustic Emission technique has its unique superiority.Work for the field of anchor,especially in high voltage tower bolt,the environment is bad,need active signal to other testing technology as excitation source,is not convenient to the practical work of detection.In this topic,Acoustic Emission technology is a kind of passive detection method,can be very light for anchor in various environment for testing. |
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