本文選題：初始缺陷　切入點(diǎn)：混凝土　出處：《鄭州大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：混凝土作為一種準(zhǔn)脆性材料,其在受到荷載作用之前,內(nèi)部就已存在微裂紋及孔隙等初始缺陷,這些初始缺陷的存在對(duì)混凝土力學(xué)性能和失效破壞有著較大的影響。目前對(duì)于混凝土初始缺陷對(duì)混凝土強(qiáng)度的影響研究多是基于數(shù)值模擬,數(shù)值模型中關(guān)于初始缺陷的結(jié)構(gòu)參數(shù)選取多是基于定性的假設(shè),因此本文基于微觀結(jié)構(gòu)試驗(yàn)獲得的初始缺陷結(jié)構(gòu)參數(shù)建立混凝土數(shù)值模型,研究初始缺陷對(duì)混凝土強(qiáng)度的影響。主要工作和結(jié)論如下:(1)確定了混凝土試驗(yàn)方案和混凝土配合比。根據(jù)拌合物坍落度及混凝土強(qiáng)度確定了混凝土試件配合比,研究了水灰比、骨料種類對(duì)混凝土初始缺陷及強(qiáng)度的影響�；炷廖⒂^結(jié)構(gòu)試驗(yàn)主要包括真空環(huán)氧浸漬技術(shù)及圖像處理技術(shù)兩個(gè)部分。(2)試驗(yàn)研究了混凝土微觀結(jié)構(gòu),定量分析了混凝土初始缺陷分布。混凝土初始缺陷定量分析技術(shù)通過對(duì)熒光圖像進(jìn)行處理獲取了混凝土初始微裂紋的總面積、長(zhǎng)度、寬度以及孔隙含量等結(jié)構(gòu)參數(shù)。結(jié)果表明:隨著水灰比的減少,混凝土界面中初始微裂紋面積占混凝土總面積的百分比及初始微裂紋平均寬度隨之減少,初始微裂紋總面積及總長(zhǎng)度隨之增大。(3)分析了初始缺陷對(duì)混凝土強(qiáng)度的影響。通過混凝土細(xì)觀結(jié)構(gòu)試驗(yàn)及宏觀強(qiáng)度試驗(yàn)分析了初始缺陷與混凝土強(qiáng)度的關(guān)系:平均寬度、孔隙含量、界面區(qū)微裂紋含量、總?cè)毕莺康臏p小,混凝土抗壓及抗拉強(qiáng)度均表現(xiàn)出增大趨勢(shì)。分析得到:界面的力學(xué)性能對(duì)混凝土力學(xué)性能影響較大。(4)建立了由粗骨料、砂漿基體、界面過渡區(qū)和初始缺陷組成的混凝土數(shù)值模型。運(yùn)用混凝土細(xì)觀數(shù)值模型模擬了混凝土單軸受壓試驗(yàn),并與宏觀強(qiáng)度試驗(yàn)結(jié)果對(duì)比。結(jié)果表明:混凝土細(xì)觀數(shù)值模型能較好的模擬混凝土單軸受壓強(qiáng)度試驗(yàn)以及混凝土破壞機(jī)理。(5)采用上述模型分析了骨料含量對(duì)混凝土強(qiáng)度的影響。建立粗骨料體積含量分別為40%、35%、25%的混凝土細(xì)觀數(shù)值模型模擬混凝土單軸受壓強(qiáng)度。模擬結(jié)果表明:在粗骨料體積含量為35%時(shí)數(shù)值模型的受壓強(qiáng)度達(dá)到最大值。
[Abstract]:As a kind of quasi-brittle material, concrete has some initial defects, such as microcracks and pores, before it is subjected to load. The existence of these initial defects has a great influence on the mechanical properties and failure failure of concrete. At present, most of the researches on the effects of initial defects on the strength of concrete are based on numerical simulation. In the numerical model, the structural parameters of the initial defects are mostly based on the qualitative hypothesis. Therefore, the numerical model of concrete is established based on the structural parameters of the initial defects obtained from the microstructure test in this paper. The effects of initial defects on concrete strength are studied. The main work and conclusions are as follows: 1) the concrete test scheme and concrete mix ratio are determined. The mix ratio of concrete specimens is determined according to the slump and strength of concrete, and the water-cement ratio is studied. The effect of aggregate types on the initial defects and strength of concrete. The microstructure test of concrete mainly includes two parts: vacuum epoxy impregnation technology and image processing technology. Quantitative analysis of initial defects in concrete. The total area and length of initial microcracks in concrete are obtained by processing fluorescence images. The results show that with the decrease of water-cement ratio, the percentage of the initial micro-crack area to the total area of concrete and the average width of the initial micro-crack decrease with the decrease of water-cement ratio. The influence of initial defects on concrete strength is analyzed by increasing the total area and total length of initial microcracks. The relationship between initial defects and concrete strength is analyzed by meso structure test and macro strength test: average width. The decrease of pore content, microcrack content and total defect content in the interface area, the compressive strength and tensile strength of concrete all show an increasing trend. It is concluded that the mechanical properties of the interface have a great influence on the mechanical properties of concrete. The concrete numerical model composed of mortar matrix, interface transition zone and initial defect is used to simulate the uniaxial compression test of concrete. The results show that the meso-numerical model of concrete can simulate uniaxial compressive strength test of concrete and failure mechanism of concrete. (5) the above model is used to analyze the effect of aggregate content on coagulation. Under the influence of soil strength, a mesoscopic numerical model for simulating uniaxial compressive strength of concrete with 40% and 35% volume content of coarse aggregate was established respectively. The simulation results show that the compressive strength of the model reaches the maximum when the volume content of coarse aggregate is 35.
【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 楊敏嘉;彭高華;周國(guó)強(qiáng);;初始缺陷對(duì)井架總體穩(wěn)定的影響[J];石油礦場(chǎng)機(jī)械;1986年01期

2 王惠德;莫經(jīng)倫;周國(guó)強(qiáng);;塔形井架基礎(chǔ)初始缺陷的統(tǒng)計(jì)分析[J];石油礦場(chǎng)機(jī)械;1987年06期

3 陳曉,戴詩(shī)亮,許可;初始缺陷對(duì)復(fù)合材料層板穩(wěn)定性的影響[J];清華大學(xué)學(xué)報(bào)(自然科學(xué)版);2001年02期

4 付光艷;;如何保證混凝土質(zhì)量探討[J];煤炭技術(shù);2006年01期

5 高麗君;;淺談混凝土裂縫的預(yù)防與處理[J];新疆有色金屬;2006年02期

6 張風(fēng);;談混凝土的施工[J];化工之友;2006年07期

7 劉景生;;功能混凝土[J];廣東建材;2007年04期

8 劉曉剛;李穎;;淺談混凝土裂縫的控制[J];糧食流通技術(shù);2007年03期

9 程e，

本文編號(hào)：1637806