界面结构和力学性能对混凝土强度影响研究

发布时间：2018-03-27 17:13

本文选题：混凝土　切入点：初始缺陷　出处：《郑州大学》2015年硕士论文

【摘要】：强度作为混凝土重要的力学性能参数,一直是研究者关注的重点。界面过渡区(ITZ)作为混凝土中联接粗骨料和砂浆基体的桥梁,其疏松的结构和较低的力学性能对混凝土的强度有较大影响。基于此,本文采用细观数值仿真方法,研究界面对混凝土强度的影响规律。主要工作和结论如下:(1)在细观层面上,认为混凝土是由粗骨料、砂浆基体、界面过渡区和初始缺陷组成的四相复合材料。基于ANSYS的二次开发技术,编写了界面初始缺陷单元在界面相中的随机分布程序,建立了含初始缺陷的混凝土细观结构模型。(2)采用有限元数值模拟技术,分析了砂浆中初始缺陷分布对砂浆强度的影响规律,提出了砂浆强度与缺陷含量间关系的理论公式。模拟计算了缺陷含量为2%~10%时的砂浆强度值,结果表明:在缺陷含量小于7%时,数值模拟结果与该理论公式吻合较好;缺陷含量高于7%时,数值模拟结果小于该理论公式值。(3)建立了由粗骨料、砂浆基体、界面过渡区和初始缺陷组成的混凝土细观计算模型。用该模型模拟了混凝土的单轴拉伸断裂破坏过程,并与宏观试验进行了对比,结果表明:本文模型能较好的模拟普通混凝土的单轴抗拉强度试验。(4)采用上述模型研究了界面结构和力学性能对混凝土抗拉强度的影响。在界面结构方面,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对混凝土单轴抗拉强度的影响;在界面力学性能方面,主要研究了界面抗拉强度和界面弹性模量对混凝土单轴抗拉强度的影响。计算结果显示:界面初始缺陷含量和界面抗拉强度对混凝土的单轴抗拉强度影响较大,当界面初始缺陷含量由10%增大到50%时混凝土抗拉强度下降了35%,当界面抗拉强度由砂浆基体强度的0.5倍增大到砂浆基体的0.9倍时混凝土的抗拉强度增大了62%;界面厚度对混凝土的单轴抗拉强度影响较小;界面初始缺陷分布位置和界面弹性模量对混凝土的抗拉强度几乎没有影响。
[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.

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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