本文選題：混凝土　切入點(diǎn)：凍融循環(huán)　出處：《長安大學(xué)》2015年碩士論文

【摘要】：混凝土作為一種常見的多相復(fù)合材料,因其所具有的較多優(yōu)點(diǎn),而廣泛應(yīng)用于各工程領(lǐng)域。有研究表明鋼筋腐蝕、凍融循環(huán)以及侵蝕環(huán)境的物理化學(xué)作用是影響混凝土耐久性能的三個(gè)重要因素,其中凍融循環(huán)對(duì)混凝土耐久性的影響愈來愈被人們所重視。特別是在我國西部寒區(qū),凍融循環(huán)作用往往是導(dǎo)致混凝土破壞的主要因素之一。因此,深入研究混凝土凍融損傷破壞過程具有非常重要的理論價(jià)值和工程實(shí)際意義。論文以西部寒區(qū)混凝土材料為研究背景,將混凝土凍融循環(huán)試驗(yàn)、宏觀力學(xué)試驗(yàn)和細(xì)觀CT掃描試驗(yàn)相結(jié)合,對(duì)混凝土材料在凍融循環(huán)下的破損機(jī)理開展研究,并利用有限元ANSYS軟件對(duì)凍融循環(huán)下混凝土進(jìn)行了數(shù)值模擬。以期更為深入地研究混凝土凍融損傷劣化機(jī)理以及破壞規(guī)律,為寒區(qū)重大工程凍融災(zāi)變預(yù)測(cè)和防治提供較可靠的試驗(yàn)與理論依據(jù)。論文研究的主要內(nèi)容如下:(1)對(duì)制備的混凝土試樣進(jìn)行凍融循環(huán)試驗(yàn),并對(duì)不同凍融循環(huán)次數(shù)下的混凝土試樣進(jìn)行單軸壓縮試驗(yàn)以及三點(diǎn)彎曲試驗(yàn)。通過研究混凝土彈性模量、抗壓強(qiáng)度、抗彎強(qiáng)度、應(yīng)力-應(yīng)變等力學(xué)特性的變化規(guī)律,探索了混凝土的宏觀力學(xué)性能與不同凍融循環(huán)次數(shù)的變化規(guī)律;(2)應(yīng)用CT技術(shù)對(duì)凍融循環(huán)下混凝土試樣的破損全過程進(jìn)行追蹤,獲得了不同凍融循環(huán)次數(shù)下混凝土細(xì)觀結(jié)構(gòu)變化特征。通過運(yùn)用圖像處理技術(shù)初步分析了凍融循環(huán)下混凝土細(xì)觀損傷擴(kuò)展的演化過程;并以圖像中CT均值的變化為基礎(chǔ),建立了基于細(xì)觀統(tǒng)計(jì)力學(xué)的損傷變量與凍融循環(huán)的關(guān)系曲線,以此對(duì)凍融循環(huán)條件下混凝土細(xì)觀結(jié)構(gòu)的損傷演化規(guī)律及破損機(jī)理進(jìn)行了定量研究;(3)利用有限元ANSYS軟件對(duì)凍融循環(huán)下混凝土試樣進(jìn)行了數(shù)值模擬,并對(duì)不同凍融循環(huán)次數(shù)下混凝土的溫度場(chǎng)分布云圖以及溫度應(yīng)力分布云圖進(jìn)行了分析,進(jìn)而驗(yàn)證了數(shù)值模擬的可行性。
[Abstract]:As a common multiphase composite material, concrete is widely used in various engineering fields because of its many advantages. The physical and chemical effects of freeze-thaw cycle and erosive environment are three important factors that affect the durability of concrete. The influence of freeze-thaw cycle on the durability of concrete is paid more and more attention, especially in the cold region of western China. Freeze-thaw cycles are often one of the main factors leading to concrete failure. It is of great theoretical value and practical significance to study the damage and failure process of concrete in freezing and thawing. In this paper, the freeze-thaw cycle test of concrete is carried out under the background of concrete materials in the western cold region. The damage mechanism of concrete material under freeze-thaw cycle was studied by combining macroscopic mechanical test and mesoscopic CT scan test. The numerical simulation of concrete under freeze-thaw cycle is carried out by using finite element ANSYS software, in order to study the mechanism of damage deterioration and failure law of concrete under freeze-thaw cycle more deeply. This paper provides a reliable experimental and theoretical basis for the prediction and prevention of freezing and thawing disasters in major projects in cold regions. The main contents of this paper are as follows: 1) Freeze-thaw cycle tests are carried out on concrete samples prepared. The uniaxial compression test and three-point bending test of concrete samples with different freeze-thaw cycles were carried out. The variation of mechanical properties of concrete such as elastic modulus, compressive strength, flexural strength, stress-strain and so on were studied. The macroscopic mechanical properties of concrete and the variation law of different freeze-thaw cycles are explored. The whole damage process of concrete samples under freeze-thaw cycle is tracked by CT technique. The variation characteristics of concrete meso-structure under different freeze-thaw cycles are obtained. The evolution process of concrete meso-damage propagation under freeze-thaw cycle is analyzed by using image processing technology, and the change of CT mean value in the image is used as the basis. The relationship curve between damage variable and freeze-thaw cycle based on meso-statistical mechanics is established. The damage evolution law and damage mechanism of concrete mesostructures under freeze-thaw cycle are studied quantitatively. The numerical simulation of concrete samples under freeze-thaw cycle is carried out by using finite element ANSYS software. The distribution of temperature field and temperature stress of concrete under different freeze-thaw cycles are analyzed, and the feasibility of numerical simulation is verified.
【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528

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