本文選題：混凝土 + 多相細(xì)觀模型　； 參考：《東南大學(xué)》2016年碩士論文

【摘要】：混凝土是一種復(fù)雜的非均質(zhì)復(fù)合材料,其失效破壞過程中的許多問題難以從用宏觀角度來解釋,而從更低一級尺度—細(xì)觀角度來研究,這些問題便迎刃而解,這是因為混凝土的細(xì)觀結(jié)構(gòu)特性在一定程度上決定了其宏觀特性。因此通過細(xì)觀研究手段來分析混凝土的宏觀特性有著重要的意義。在細(xì)觀層面上混凝土的粗骨料表面包裹著一層性質(zhì)與水泥砂漿迥異的區(qū)域—界面過渡區(qū)(簡稱ITZ),它對混凝土的宏觀特征有很大的影響。本文建立了一種全新的界面過渡區(qū)模型,該模型考慮了界面過渡區(qū)細(xì)觀結(jié)構(gòu)的非均質(zhì)特征,體現(xiàn)了其力學(xué)性質(zhì)的梯度特性,為研究混凝土的整體特性奠定了基礎(chǔ)。論文主要成果如下：建立了考慮隨機孔洞的水化水泥漿體數(shù)值模型,對該模型進(jìn)行了單軸受拉模擬,分析了其荷載—位移全曲線與裂縫的開展過程。通過大量數(shù)值計算,得到了細(xì)觀結(jié)構(gòu)變化對水化水泥漿體宏觀特性的影響,為定性地研究界面過渡區(qū)的力學(xué)性質(zhì)奠定了基礎(chǔ)。對混凝土的界面過渡區(qū)進(jìn)行了分層處理,并以此為基礎(chǔ)建立了考慮非均質(zhì)界面過渡區(qū)的混凝土多相細(xì)觀模型,與傳統(tǒng)模型相比該模型更接近于界面過渡區(qū)實際狀況。將數(shù)值計算結(jié)果與試驗結(jié)果進(jìn)行對比,驗證了模型的準(zhǔn)確性與穩(wěn)定性,并分析了界面過渡區(qū)分層處理對計算精度的影響。以PYTHON語言為基礎(chǔ)對ABAQUS進(jìn)行二次開發(fā),編寫了一套集模型建立、計算和后處理為一體的程序,節(jié)省了大量建模與調(diào)試的時間,解決了建模和計算分開操作時產(chǎn)生的不兼容問題。運用本文建立的數(shù)值模型,研究了各相細(xì)觀材料參數(shù)改變對混凝土宏觀特性的影響,并分析了三點彎曲梁的荷載—位移全曲線與裂縫開展過程,通過模擬發(fā)現(xiàn)本文建立的混凝土多相細(xì)觀模型能夠較好的反映混凝土細(xì)觀結(jié)構(gòu)變化對宏觀特性的影響,突出了界面過渡區(qū)在混凝土失效破壞過程中所起到的作用,體現(xiàn)出了混凝土細(xì)觀結(jié)構(gòu)與宏觀特性的聯(lián)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.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TU528

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本文編號：1965152