本文選題：水工混凝土 + 線性分布　； 參考：《重慶交通大學(xué)》2017年碩士論文

【摘要】：隨著水利工程的發(fā)展,水工建筑物對(duì)于混凝土性能的要求逐步增加,而混凝土出現(xiàn)的裂縫問題也成為本行業(yè)關(guān)注的焦點(diǎn)之一,對(duì)于斷裂過程區(qū)的研究是混凝土斷裂特性研究的基礎(chǔ)。本文主要通過使用先進(jìn)的數(shù)字圖像相關(guān)方法測(cè)量技術(shù)技術(shù),對(duì)試件在三點(diǎn)彎曲實(shí)驗(yàn)中的表面應(yīng)變場(chǎng)進(jìn)行分析。在目前的斷裂力學(xué)理論的基礎(chǔ)上,通過簡(jiǎn)化軟化曲線模型,利用MATLAB軟件編程進(jìn)行了基于過程區(qū)位移線性分布的斷裂過程區(qū)的特性研究,本文的幾個(gè)主要工作如下:(1)通過數(shù)字圖像相關(guān)方法觀測(cè)記錄三點(diǎn)彎曲實(shí)驗(yàn)中整個(gè)試件的全場(chǎng)位移應(yīng)變變化情況,對(duì)比引伸計(jì)測(cè)量數(shù)值,驗(yàn)證了數(shù)字圖像相關(guān)方法的準(zhǔn)確性。從全場(chǎng)應(yīng)變分析,發(fā)現(xiàn)隨著荷載的增加,全場(chǎng)應(yīng)變會(huì)出現(xiàn)應(yīng)變集中的現(xiàn)象,主要在裂縫發(fā)展過程的周圍區(qū)域。另外,通過對(duì)裂縫尖端切線的不同高度平行線的位移分析,其突變區(qū)域也可以判斷裂縫存在的區(qū)域以及斷裂裂縫存在的走向。(2)為了解水工建筑物的斷裂過程,分別進(jìn)行了飽和混凝土與非飽和混凝土試件的三點(diǎn)彎曲實(shí)驗(yàn)。通過二者的表現(xiàn)規(guī)律,發(fā)現(xiàn)二者呈現(xiàn)相同的變化趨勢(shì),表明二者的斷裂過程發(fā)展應(yīng)該有相同的規(guī)律,所以可以將非飽和混凝土的斷裂過程區(qū)的研究的一些結(jié)論運(yùn)用到飽和混凝土上來。(3)對(duì)于斷裂過程區(qū)發(fā)展的研究,主要通過分析斷裂過程區(qū)與混凝土試件所受到荷載的關(guān)系,發(fā)現(xiàn)斷裂過程區(qū)是在荷載達(dá)到一定值后才開始發(fā)生,產(chǎn)生之后伴隨整個(gè)受載過程,受邊界條件影響,后期到達(dá)一定臨界值時(shí),斷裂過程區(qū)長(zhǎng)度會(huì)下降。(4)對(duì)裂縫周邊應(yīng)變進(jìn)行相關(guān)分析,發(fā)現(xiàn)裂縫尖端周圍不同區(qū)域應(yīng)變值的變化規(guī)律與所取分析長(zhǎng)度關(guān)系不大,但會(huì)影響其峰值的大小;所取分析長(zhǎng)度的中心距離裂縫的距離會(huì)影響應(yīng)變的變化規(guī)律。(5)在前人的斷裂理論模型上,假定張開位移呈線性分布,得到一種較為簡(jiǎn)單、快速軟化曲線參數(shù)的獲取方式。根據(jù)本文建立的軟化曲線模型,通過對(duì)不同強(qiáng)度、不同含水率、不同骨料、不同砂率、不同骨料最大粒徑以及不同粗骨料含量進(jìn)行相關(guān)擬合對(duì)比,得到相應(yīng)影響關(guān)系。
[Abstract]:With the development of water conservancy engineering, the demand for concrete performance of hydraulic structures is increasing gradually, and the crack problem of concrete has become one of the focal points of the industry. The study of fracture process zone is the basis of the study on fracture characteristics of concrete. In this paper, the surface strain field of the specimen in three point bending experiment is analyzed by using the advanced digital image correlation method. On the basis of the current fracture mechanics theory and by simplifying the softening curve model, the characteristics of the fracture process area based on the linear distribution of the displacement in the process zone are studied by using MATLAB software. The main work of this paper is as follows: (1) the whole displacement and strain changes of the whole specimen in the three-point bending experiment are recorded by the digital image correlation method, and the accuracy of the digital image correlation method is verified by comparing the measured values with the extensometer. From the full-field strain analysis, it is found that with the increase of the load, the full-field strain will be concentrated, mainly in the area around the crack development process. In addition, by analyzing the displacement of parallel lines at different height of the tangent line at the crack tip, the abrupt region can also be used to judge the fracture zone and the strike of the fracture crack. (2) in order to understand the fracture process of hydraulic structures, The three-point bending tests of saturated concrete and unsaturated concrete were carried out respectively. It is found that the two show the same trend of change, which indicates that the fracture process of both should have the same law. Therefore, some conclusions of the fracture process zone of unsaturated concrete can be applied to the saturated concrete. (3) the research on the development of the fracture process zone is mainly based on the analysis of the relationship between the fracture process zone and the load on the concrete specimen. It is found that the fracture process zone does not begin until the load reaches a certain value, followed by the whole loading process, affected by the boundary conditions, and when the critical value is reached at the later stage. The length of fracture zone will decrease. (4) through the correlation analysis of the strain around the crack tip, it is found that the variation of strain values in different regions around the crack tip is not related to the length of the analysis, but it will affect the magnitude of the peak value. The distance between the center and the crack of the analyzed length will affect the variation of strain. (5) in the former fracture theory model, the opening displacement is assumed to be linear distribution, and a simple and fast softening curve parameter is obtained. According to the softening curve model established in this paper, through the correlation and comparison of different strength, different moisture content, different aggregate, different sand ratio, different aggregate maximum particle size and different coarse aggregate content, the corresponding influence relation was obtained.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TV431

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

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本文編號(hào)：2063452