本文選題：混凝土　切入點：初始缺陷　出處：《鄭州大學(xué)》2015年碩士論文

【摘要】：強(qiáng)度作為混凝土重要的力學(xué)性能參數(shù),一直是研究者關(guān)注的重點。界面過渡區(qū)(ITZ)作為混凝土中聯(lián)接粗骨料和砂漿基體的橋梁,其疏松的結(jié)構(gòu)和較低的力學(xué)性能對混凝土的強(qiáng)度有較大影響�；诖�,本文采用細(xì)觀數(shù)值仿真方法,研究界面對混凝土強(qiáng)度的影響規(guī)律。主要工作和結(jié)論如下:(1)在細(xì)觀層面上,認(rèn)為混凝土是由粗骨料、砂漿基體、界面過渡區(qū)和初始缺陷組成的四相復(fù)合材料�；贏NSYS的二次開發(fā)技術(shù),編寫了界面初始缺陷單元在界面相中的隨機(jī)分布程序,建立了含初始缺陷的混凝土細(xì)觀結(jié)構(gòu)模型。(2)采用有限元數(shù)值模擬技術(shù),分析了砂漿中初始缺陷分布對砂漿強(qiáng)度的影響規(guī)律,提出了砂漿強(qiáng)度與缺陷含量間關(guān)系的理論公式。模擬計算了缺陷含量為2%~10%時的砂漿強(qiáng)度值,結(jié)果表明:在缺陷含量小于7%時,數(shù)值模擬結(jié)果與該理論公式吻合較好;缺陷含量高于7%時,數(shù)值模擬結(jié)果小于該理論公式值。(3)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細(xì)觀計算模型。用該模型模擬了混凝土的單軸拉伸斷裂破壞過程,并與宏觀試驗進(jìn)行了對比,結(jié)果表明:本文模型能較好的模擬普通混凝土的單軸抗拉強(qiáng)度試驗。(4)采用上述模型研究了界面結(jié)構(gòu)和力學(xué)性能對混凝土抗拉強(qiáng)度的影響。在界面結(jié)構(gòu)方面,主要研究了界面厚度、界面初始缺陷位置和界面初始缺陷含量對混凝土單軸抗拉強(qiáng)度的影響;在界面力學(xué)性能方面,主要研究了界面抗拉強(qiáng)度和界面彈性模量對混凝土單軸抗拉強(qiáng)度的影響。計算結(jié)果顯示:界面初始缺陷含量和界面抗拉強(qiáng)度對混凝土的單軸抗拉強(qiáng)度影響較大,當(dāng)界面初始缺陷含量由10%增大到50%時混凝土抗拉強(qiáng)度下降了35%,當(dāng)界面抗拉強(qiáng)度由砂漿基體強(qiáng)度的0.5倍增大到砂漿基體的0.9倍時混凝土的抗拉強(qiáng)度增大了62%;界面厚度對混凝土的單軸抗拉強(qiáng)度影響較小;界面初始缺陷分布位置和界面彈性模量對混凝土的抗拉強(qiáng)度幾乎沒有影響。
[Abstract]:The mechanical properties of concrete strength as an important parameter, has been the focus of researchers. The interfacial transition zone (ITZ) as a bridge in the concrete connection matrix of coarse aggregate and mortar, has great influence on strength of the porous structure and low mechanical property of concrete. Based on this, this paper uses meso numerical simulation method. Study on the influence of the interface on the strength of concrete. The main work and conclusions are as follows: (1) at the mesoscopic level, that the concrete is composed of coarse aggregate, mortar matrix and interfacial transition zone composition and initial defect of four phase composite materials. Two development technology based on ANSYS, compiled randomly distributed program interface initial defect unit in the interface phase, established with initial defects of concrete meso structure model. (2) by using the finite element numerical simulation technology, analyzes the influence on the strength of the mortar mortar in the initial distribution of defects, Put forward the theoretical formula of mortar strength and defects between content. The content of simulation for the defects of mortar strength 2%~10%, results show that the defect content is less than 7%, the numerical simulation results agree well with the theoretical formula; the defect content is higher than 7%, the results of numerical simulation is less than the value of the theoretical formula (3). Established by the coarse aggregate, mortar matrix and interfacial transition zone, composed of initial defects of concrete meso model. This model is used to simulate the uniaxial tensile fracture of concrete failure process, and compared with the macro test, the results show that the model can simulate the uniaxial tensile strength test of ordinary concrete better. (4) the effects of the interface structure and mechanical properties of the tensile strength of concrete by using the model. The interface structure, mainly on the interface thickness, interface initial defect position and the initial lack of interface Effect of depression content on uniaxial tensile strength of concrete; interface in mechanical properties, mainly studied the influence of interface tensile strength and interfacial elastic modulus on the uniaxial tensile strength of concrete. The calculation results show that the interface initial defect content and interfacial tensile strength of concrete uniaxial tensile strength is affected by the interface when the initial defect content 10% increased to 50% when the concrete tensile strength decreased by 35%, the tensile strength of the interface when the tensile strength by 0.5 times the strength of mortar increased to 0.9 times of mortar matrix of concrete increased by 62%; the smaller the thickness of interface of uniaxial tensile strength of concrete; almost no effect on tensile strength of concrete interface initial defect location and the interfacial elastic modulus.

【學(xué)位授予單位】：鄭州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU528

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本文編號：1672461