基于声发射技术的锚杆腐蚀的检测与信号处理研究

发布时间：2018-06-12 17:16

本文选题：锚杆 + 声发射技术　；参考：《昆明理工大学》2017年硕士论文

【摘要】：锚杆是用来支护基础设施的核心构件,它被埋于地下,依靠和周围的岩石相互作用来稳固基础设施。因此,锚杆的质量直接影响着它所支撑的工程的稳定性。而锚杆的质量受到地质因素、天气变化等各种因素的影响,经常会在表面或者截面发生腐蚀,使锚杆的安全运营存在长久的隐患,大多数的工程事故都是由于锚杆的腐蚀造成的。而现阶段检测锚杆的手段都存在一些不足,有时强调了实时性而忽略了锚杆的耐久性,而且抽样检测并不能从根本上解决问题,总之传统的使用的检测方法不能做到统筹兼顾。其他的一些关于锚杆的无损检测方法也存在着各种各样的缺陷。所以,本课题提出了一种基于声发射技术的检测锚杆质量的方法,该方法是一种新兴的简便高效的检测手段,并且这是声发射技术在锚杆腐蚀检测的首次应用,因此作为本课题主要的研究方向。本课题的主要研究的内容分为以下几个步骤:1)利用以经典力学和弹性力学为基础的波动理论分别推导出了锚杆在一维自由度状态和在锚固状态的振动规律,同时也推导出在外部的瞬态激振的激励下,锚杆内应力波的产生和传播规律,这些都是为之后的制作声发射传感器提供了理论依据和参数指标。2)介绍声发射技术的内容,包括声发射的检测原理,信号类型和信号分析方法。并且分析了应力波锚杆在锚杆一端锚固一段自由的状态下,即在两种不同的介质界面处的传播特性。3)根据前一章分析的结果,通过对锚杆的声发射信号的一些特性比如频率特性、频带宽度、噪声等,采用一种有机压电材料PVDF作为主要的换能元件,并设计了三级前置放大电路、陷波电路和供电电路,制作了一种适用于本课题中锚杆的腐蚀检测的声发射传感器。4)信号的处理,先是阐述了各种方法基本原理,根据对本课题采集到的信号的特性,决定采用时频分析法对实验数据进行处理。在实验阶段,对三个试验锚杆样本采集的数据分别进行短时傅里叶变换和S变换,得到了时频图,综合两种分析方法处理后的结果得出了锚杆试验样本的信号特征。5)然后在某现场进行实验验证,对现场的正在服役的锚杆采用同样的实验方法来采集现场锚杆的信号,经过同样的处理后,发现在实验室得到的信号特征与现场锚杆的信号特征极其相似,这些特征可以用来描述锚杆的质量情况,验证了声发射技术在此领域应用的可行性。本课题的创新的是在于首次将声发射技术应用在锚杆的腐蚀检测领域中,而且经过研究对比发现,声发射技术有其独特的优越性。对于野外工作的锚杆,特别是在高压电塔架的锚杆中,环境比较恶劣,其他的检测技术都需要有源信号来作为激励源,不便于实际工作的检测。而在本课题中,声发射技术是一种无源的检测方法,可以很轻便地对处于各种环境中的锚杆进行检测。
[Abstract]:Anchor is the core component used to support the infrastructure. It is buried underground and depends on the interaction with surrounding rocks to stabilize the infrastructure. Therefore, the quality of anchor directly affects the stability of the project it supports. The quality of the bolt is affected by geological factors, weather changes and other factors, often corrosion occurs on the surface or cross-section, so that the safety of the bolt has a long-term hidden danger. Most engineering accidents are caused by corrosion of anchors. At the present stage, there are some shortcomings in the method of detecting anchor rod. Sometimes, the durability of anchor rod is neglected, and the sampling test can not solve the problem fundamentally. In short, the traditional detection method can not be used in an integrated way. Other non-destructive testing methods for anchors also have a variety of defects. Therefore, a new method based on acoustic emission (AE) technology is proposed to detect the quality of anchor rod. This method is a new, simple and efficient method, and it is the first application of AE technology in the detection of anchor corrosion. Therefore, as the main research direction of this topic. The main contents of this paper are divided into the following steps: 1) by using the wave theory based on classical mechanics and elastic mechanics, the vibration laws of anchors in one-dimensional degree of freedom state and in anchoring state are derived, respectively. At the same time, under the excitation of external transient excitation, the law of the generation and propagation of stress wave in the bolt is deduced, which provides the theoretical basis and parameter index. 2) the content of the acoustic emission technology is introduced. Including acoustic emission detection principle, signal type and signal analysis method. The propagation characteristics of stress wave anchors under the condition of anchoring one end of the anchor for a free section, I. E. at the interface of two different media. 3) are analyzed according to the results of the previous chapter. Based on the characteristics of acoustic emission signal of anchor rod, such as frequency characteristic, frequency band width, noise and so on, a kind of organic piezoelectric material PVDF is used as the main energy transfer element, and a three-stage preamplifier circuit, notch circuit and power supply circuit are designed. In this paper, a kind of acoustic emission sensor. 4) signal processing suitable for the corrosion detection of anchor rod is made. Firstly, the basic principles of various methods are expounded, and according to the characteristics of the signals collected in this subject, It is decided to use time-frequency analysis method to process the experimental data. In the experiment stage, the data collected from the three test bolt samples were analyzed by short time Fourier transform (STFT) and S transform respectively, and the time-frequency diagram was obtained. After synthesizing the results of the two analysis methods, the signal characteristics of the anchor test sample. 5) and then the experimental verification is carried out in a certain field. The same experimental method is used to collect the field anchor signal for the in-service anchor in the field. After the same treatment, it is found that the characteristics of the signals obtained in the laboratory are very similar to those of the field anchors. These characteristics can be used to describe the quality of the anchors and verify the feasibility of the application of acoustic emission technology in this field. The innovation of this subject lies in the first application of acoustic emission technology in the field of corrosion detection of anchor rod, and it is found that acoustic emission technology has its unique advantages. For the field working anchor, especially in the high voltage tower, the environment is relatively bad, and other detection techniques need active signal as the excitation source, which is not convenient for practical detection. In this paper, acoustic emission (AE) is a passive detection method, which can be used to detect anchors in various environments.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD350.5

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