本文選題：纖維混凝土 + 隨機(jī)骨料模型　； 參考：《長(zhǎng)安大學(xué)》2014年碩士論文

【摘要】：纖維混凝土具有高延性和高韌性優(yōu)點(diǎn)，在土木工程等領(lǐng)域中得到廣泛的應(yīng)用，但目前研究仍以宏觀試驗(yàn)和定性分析為主，缺乏成熟的細(xì)觀力學(xué)模型，對(duì)其細(xì)觀力學(xué)性能與宏觀力學(xué)行為之間關(guān)聯(lián)性的研究仍較少見。本文從細(xì)觀角度出發(fā)，采用細(xì)觀損傷力學(xué)理論和數(shù)值模擬技術(shù)，建立纖維混凝土細(xì)觀力學(xué)模型，探究纖維混凝土損傷與斷裂過(guò)程中裂紋擴(kuò)展規(guī)律以及損傷與斷裂機(jī)制問(wèn)題。 本文首先在細(xì)觀層次上把纖維混凝土看作是由粗集料、硬化纖維砂漿基體和兩者之間界面過(guò)渡區(qū)所組成的三相非均勻復(fù)合材料，，基于Monte-Carlo隨機(jī)抽樣方法，分析了混凝土內(nèi)部不同骨料的形狀幾何信息，提出了混凝土骨料隨機(jī)投放算法，建立了基于不同骨料含量和不同骨料形狀的纖維混凝土細(xì)觀結(jié)構(gòu)數(shù)值模型。 基于分水嶺分割等圖像處理技術(shù)對(duì)纖維混凝土隨機(jī)截面進(jìn)行了數(shù)字圖像處理和分析，通過(guò)矢量轉(zhuǎn)換技術(shù)建立了基于纖維混凝土真實(shí)骨料分布的細(xì)觀結(jié)構(gòu)模型。利用粗集料的圓度、針狀系數(shù)和Blaschke系數(shù)等參數(shù)定量分析了混凝土內(nèi)部粗集料的形狀特征，并利用粗集料主軸傾角和級(jí)配這兩個(gè)指標(biāo)定量分析了混凝土內(nèi)部粗集料的空間分布特征。 從混凝土材料的細(xì)觀結(jié)構(gòu)入手，通過(guò)室內(nèi)力學(xué)性能試驗(yàn)和細(xì)觀損傷理論研究，建立了適合描述三相細(xì)觀介質(zhì)力學(xué)特征的本構(gòu)關(guān)系。利用有限元技術(shù)對(duì)纖維混凝土單軸受壓和彎拉試驗(yàn)進(jìn)行了數(shù)值模擬，模擬結(jié)果能夠較好地反應(yīng)出纖維混凝土在不同受力狀態(tài)下的應(yīng)力應(yīng)變特點(diǎn)以及損傷與斷裂過(guò)程。 采用細(xì)觀數(shù)值模擬試驗(yàn)分析了粗集料形狀和粗集料含量對(duì)纖維混凝土力學(xué)性能的影響。分析結(jié)果表明，粗集料形狀對(duì)纖維混凝土彎拉強(qiáng)度的影響大于抗壓強(qiáng)度；粗集料含量的增加顯著地提高纖維混凝土的抗壓和抗彎拉強(qiáng)度，且粗集料含量增加一定程度上增大了纖維混凝土脆性破壞概率。
[Abstract]:Fiber concrete has the advantages of high ductility and high toughness , and is widely used in the fields of civil engineering and other fields . However , the present research is still mainly based on macro - test and qualitative analysis .

In this paper , the fiber concrete is regarded as a three - phase non - uniform composite material composed of coarse aggregate , hardened fiber mortar matrix and interface transition area between them . Based on Monte - Carlo random sampling method , the shape geometry information of different aggregate inside the concrete is analyzed , the random throwing algorithm of concrete aggregate is put forward , and the numerical model of fiber concrete meso - structure based on different aggregate content and different aggregate shapes is established .

Based on watershed segmentation and other image processing techniques , the random section of fiber concrete is subjected to digital image processing and analysis , and a meso - structure model based on the real aggregate distribution of fiber - concrete is established through vector conversion technology . The shape characteristics of coarse aggregate in concrete are analyzed quantitatively by using the parameters such as roundness , needle - like coefficient of coarse aggregate and Blakeske coefficient , and the spatial distribution characteristics of coarse aggregate in concrete are analyzed quantitatively by using the inclination angle and gradation of coarse aggregate .

Based on the meso - structure of concrete material , this paper has established the constitutive relation suitable for describing the mechanical characteristics of three - phase meso - mesoscopic medium by means of indoor mechanical property test and meso - view damage theory . The finite element technique is used to simulate the uniaxial compression and bending test of fiber concrete . The simulation results can reflect the stress - strain characteristics and damage and fracture process of fiber concrete under different stress states .

The influence of coarse aggregate shape and coarse aggregate content on the mechanical properties of fiber concrete is analyzed by means of numerical simulation test . The results show that the influence of coarse aggregate shape on the flexural strength of fiber concrete is greater than that of compressive strength ;
The increase of coarse aggregate content significantly increases the compressive strength and flexural tensile strength of fiber concrete , and increases the probability of brittle failure of fiber concrete to some extent .

【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU528

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