發(fā)布時(shí)間：2019-05-28 07:13

【摘要】：混凝土橋占橋梁總數(shù)的90%,絕大多數(shù)既有混凝土橋梁存在一定的損傷。既有混凝土橋的損傷是影響橋梁使用性能的重要因素。聲發(fā)射技術(shù)是檢測(cè)混凝土損傷的有效方法,聲發(fā)射檢測(cè)信號(hào)與混凝土內(nèi)部損傷對(duì)應(yīng)關(guān)系研究還不深入,本論文針對(duì)聲發(fā)射信號(hào)與混凝土損傷進(jìn)行研究,具體工作如下:(1)對(duì)混凝土試件進(jìn)行三分點(diǎn)加載彎曲試驗(yàn),監(jiān)測(cè)加載全過(guò)程混凝土應(yīng)變和聲發(fā)射特征參數(shù),分析試件不同受力階段聲發(fā)射特征參數(shù)與損傷關(guān)系�；炷猎嚰虞d初期,水泥砂漿和集料的界面存在的微裂縫等原始缺陷,就會(huì)產(chǎn)生低幅值、低能量的撞擊信號(hào),隨著荷載的繼續(xù)加大,試件內(nèi)部不斷產(chǎn)生新的裂縫,聲發(fā)射信號(hào)活動(dòng)增強(qiáng),高幅值信號(hào)出現(xiàn)次數(shù)增多,同時(shí)伴隨著能量的多次突發(fā)釋放。(2)基于小波理論,分析研究了適用于混凝土試件的小波去噪?yún)?shù)選擇,當(dāng)選用db4小波、進(jìn)行2層小波分解,在Heursure閾值準(zhǔn)則下選用軟閾值函數(shù)進(jìn)行數(shù)據(jù)去噪處理是效果最理想的。通過(guò)比對(duì)去噪前后信號(hào)波形圖,可以看出運(yùn)用小波降噪,處理信號(hào)保留了原始信號(hào)的大部分主要特征,同時(shí)去除了一些噪聲信號(hào),使采集到的信號(hào)更能表征聲發(fā)射源信號(hào)的特征。(3)在對(duì)采集到的信號(hào)進(jìn)行小波降噪的基礎(chǔ)上,運(yùn)用互相關(guān)分析法,計(jì)算出兩兩傳感器接收到聲發(fā)射信號(hào)的時(shí)間延遲,進(jìn)而結(jié)合所測(cè)時(shí)間波速就可以定位出聲發(fā)射源位置,提高了聲發(fā)射損傷定位的精確性。
[Abstract]:Concrete bridges account for 90% of the total number of bridges, and most of the existing concrete bridges have certain damage. The damage of existing concrete bridge is an important factor affecting the performance of bridge. Acoustic emission technology is an effective method to detect concrete damage. The corresponding relationship between acoustic emission detection signal and concrete internal damage is not deeply studied. In this paper, the acoustic emission signal and concrete damage are studied. The specific work is as follows: (1) the three-point loading bending test of concrete specimens is carried out, the strain and acoustic emission characteristic parameters of concrete are monitored, and the relationship between acoustic emission characteristic parameters and damage in different stress stages is analyzed. At the beginning of loading, the original defects such as micro cracks in the interface between cement mortar and aggregate will produce low amplitude and low energy impact signals. with the continuous increase of load, new cracks will continue to occur in the specimen. The activity of acoustic emission signal is enhanced, the frequency of high amplitude signal is increased, and the sudden release of energy is accompanied by multiple bursts of energy. (2) based on wavelet theory, the selection of wavelet denoising parameters suitable for concrete specimens is analyzed and studied, and db4 wavelet is selected. The two-layer wavelet decomposition is carried out, and the soft threshold function is selected for data denoising under the Heursure threshold criterion. By comparing the signal waveform before and after denoising, we can see that by using wavelet denoising, the processed signal preserves most of the main characteristics of the original signal, and at the same time removes some noise signals. The collected signal can better represent the characteristics of the acoustic emission source signal. (3) on the basis of wavelet denoising of the collected signal, the time delay of receiving the acoustic emission signal by the pairwise sensor is calculated by using the cross-correlation analysis method. Combined with the measured time wave velocity, the position of acoustic emission source can be located, and the accuracy of acoustic emission damage location can be improved.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U441.4

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 史攀飛;劉京紅;楊躍飛;高洋;;不同初始損傷混凝土單軸壓縮分形特征分析[J];混凝土;2016年04期

2 劉茂軍;王根偉;吳麗琴;;基于聲發(fā)射技術(shù)的單軸受壓混凝土損傷細(xì)觀研究[J];科學(xué)技術(shù)與工程;2015年01期

3 王巖;張友桃;胡鴻翔;劉紹俊;袁亮;;基于聲發(fā)射和人工神經(jīng)網(wǎng)絡(luò)的混凝土損傷程度識(shí)別[J];建筑材料學(xué)報(bào);2014年04期

4 賴于樹(shù);熊燕;程龍飛;;受載混凝土破壞全過(guò)程聲發(fā)射信號(hào)頻帶能量特征[J];振動(dòng)與沖擊;2014年10期

5 韓亮;樊健生;;近年國(guó)內(nèi)橋梁垮塌事故分析及思考[J];公路;2013年03期

6 丁幼亮;鄧揚(yáng);李愛(ài)群;;聲發(fā)射技術(shù)在橋梁結(jié)構(gòu)健康監(jiān)測(cè)中的應(yīng)用研究進(jìn)展[J];防災(zāi)減災(zāi)工程學(xué)報(bào);2010年03期

7 李冬生;歐進(jìn)萍;;橋梁拉索損傷聲發(fā)射監(jiān)測(cè)及其臨界損傷判斷[J];預(yù)應(yīng)力技術(shù);2009年05期

8 陳明憲;;從鳳凰堤溪大橋事故談石拱橋[J];公路工程;2008年03期

9 李冬生;歐進(jìn)萍;;鋼絞線拉伸過(guò)程中的聲發(fā)射特征及其損傷演化模型[J];公路交通科技;2007年09期

10 趙雷;蔡琦;姚祺峰;陳玲;;聲發(fā)射技術(shù)用于診斷船舶汽輪發(fā)電機(jī)組碰摩故障的研究[J];中國(guó)修船;2007年02期

相關(guān)碩士學(xué)位論文 前3條

1 修黎明;橋梁結(jié)構(gòu)的損傷檢測(cè)與識(shí)別技術(shù)研究[D];濟(jì)南大學(xué);2009年

2 張順祥;混凝土軸心受拉聲發(fā)射Kaiser效應(yīng)試驗(yàn)研究[D];河海大學(xué);2007年

3 王彬;基于聲發(fā)射技術(shù)的預(yù)應(yīng)力混凝土損傷檢測(cè)理論及應(yīng)用[D];江蘇大學(xué);2006年

，

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