考虑非均质界面过渡区的混凝土多相细观模型

发布时间：2018-06-01 18:09

本文选题：混凝土 + 多相细观模型　；参考：《东南大学》2016年硕士论文

【摘要】：混凝土是一种复杂的非均质复合材料,其失效破坏过程中的许多问题难以从用宏观角度来解释,而从更低一级尺度—细观角度来研究,这些问题便迎刃而解,这是因为混凝土的细观结构特性在一定程度上决定了其宏观特性。因此通过细观研究手段来分析混凝土的宏观特性有着重要的意义。在细观层面上混凝土的粗骨料表面包裹着一层性质与水泥砂浆迥异的区域—界面过渡区(简称ITZ),它对混凝土的宏观特征有很大的影响。本文建立了一种全新的界面过渡区模型,该模型考虑了界面过渡区细观结构的非均质特征,体现了其力学性质的梯度特性,为研究混凝土的整体特性奠定了基础。论文主要成果如下：建立了考虑随机孔洞的水化水泥浆体数值模型,对该模型进行了单轴受拉模拟,分析了其荷载—位移全曲线与裂缝的开展过程。通过大量数值计算,得到了细观结构变化对水化水泥浆体宏观特性的影响,为定性地研究界面过渡区的力学性质奠定了基础。对混凝土的界面过渡区进行了分层处理,并以此为基础建立了考虑非均质界面过渡区的混凝土多相细观模型,与传统模型相比该模型更接近于界面过渡区实际状况。将数值计算结果与试验结果进行对比,验证了模型的准确性与稳定性,并分析了界面过渡区分层处理对计算精度的影响。以PYTHON语言为基础对ABAQUS进行二次开发,编写了一套集模型建立、计算和后处理为一体的程序,节省了大量建模与调试的时间,解决了建模和计算分开操作时产生的不兼容问题。运用本文建立的数值模型,研究了各相细观材料参数改变对混凝土宏观特性的影响,并分析了三点弯曲梁的荷载—位移全曲线与裂缝开展过程,通过模拟发现本文建立的混凝土多相细观模型能够较好的反映混凝土细观结构变化对宏观特性的影响,突出了界面过渡区在混凝土失效破坏过程中所起到的作用,体现出了混凝土细观结构与宏观特性的联系。
[Abstract]:Concrete is a kind of complex heterogeneous composite material. Many problems in the process of failure and failure of concrete are difficult to be explained from a macro perspective, but studied from a lower order scale-meso perspective, and these problems can be easily solved. This is because the meso-structure characteristics of concrete to some extent determine its macro-properties. Therefore, it is of great significance to analyze the macroscopic characteristics of concrete by means of meso-research. On the meso-level, the coarse aggregate surface of concrete is surrounded by a region-interface transition zone (ITZA), which is different in nature from cement mortar, which has a great influence on the macroscopic characteristics of concrete. In this paper, a new interfacial transition zone model is established. The model takes into account the heterogeneous characteristics of mesoscopic structures in the interfacial transition zone and reflects the gradient properties of its mechanical properties, which lays a foundation for the study of the overall properties of concrete. The main achievements of this paper are as follows: a numerical model of hydrated cement paste considering random holes is established. The uniaxial tensile simulation of the model is carried out and the load-displacement curve and the process of crack development are analyzed. Through a large number of numerical calculations, the influence of the meso-structure change on the macroscopic properties of hydrated cement paste is obtained, which lays a foundation for the qualitative study of the mechanical properties of the interfacial transition zone. The multi-phase mesoscopic model of concrete considering heterogeneous interfacial transition zone is established on the basis of delamination treatment of the interfacial transition zone of concrete. Compared with the traditional model, the model is closer to the actual condition of the interfacial transition zone. The accuracy and stability of the model are verified by comparing the numerical results with the experimental results, and the influence of the interface transition layer processing on the calculation accuracy is analyzed. Based on the second development of ABAQUS based on PYTHON language, a set of program which integrates model building, calculation and post-processing is written, which saves a lot of time for modeling and debugging, and solves the incompatibility problem when modeling and computing are operated separately. By using the numerical model established in this paper, the influence of the change of material parameters on the macroscopic properties of concrete is studied, and the load-displacement curve and crack development process of three-point bending beam are analyzed. Through the simulation, it is found that the multi-phase meso model of concrete can reflect the influence of the change of the meso structure of concrete on the macroscopic characteristics, and the function of the interfacial transition zone in the process of failure and failure of concrete is highlighted. The relation between the mesoscopic structure of concrete and the macroscopic characteristic is embodied.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU528

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