本文選題：混凝土　切入點：凍融蠕變　出處：《中國礦業(yè)大學》2016年博士論文

【摘要】：隨著我國發(fā)展西部,振興東北老工業(yè)區(qū),“一帶一路”等戰(zhàn)略的實施,許多大型混凝土結(jié)構(gòu)工程建設(shè)迅速展開,這類工程對人民生活和經(jīng)濟發(fā)展起到重要作用,但嚴酷的環(huán)境條件使其壽命大大縮減,其中凍融環(huán)境對混凝土結(jié)構(gòu)產(chǎn)生的危害給國家?guī)碇卮蠼?jīng)濟損失。凍融環(huán)境下混凝土的蠕變特性及損傷破裂機理研究是解決這類工程結(jié)構(gòu)耐久性問題的基礎(chǔ)。本文以粉煤灰混凝土為研究對象,借助于KDS-60快速凍融實驗機、微機控制電液伺服蠕變試驗系統(tǒng)等現(xiàn)代測試技術(shù),綜合應(yīng)用理論分析,試驗研究等方法與手段,對凍融作用后粉煤灰混凝土的一般力學特性、蠕變特性、宏觀破裂特征、微細觀孔結(jié)構(gòu)及斷口特征、理論流變力學模型、凍融蠕變損傷破裂機理等進行了系統(tǒng)研究。主要取得如下研究成果:(1)借助于快速凍融試驗機和微機控制電液伺服蠕變試驗系統(tǒng),對未摻加粉煤灰的高強混凝土進行凍融蠕變試驗研究,得到了蠕變時程曲線,峰值應(yīng)力、峰值應(yīng)變、彈性模量、蠕變變形模量、瞬時應(yīng)變、蠕變速率、宏觀破裂特征等隨凍融次數(shù)的變化規(guī)律。(2)系統(tǒng)測定了粉煤灰混凝土的蠕變特性和凍融蠕變特性,得到了蠕變模量、蠕變速率等隨粉煤灰摻量的變化規(guī)律,得到了粉煤灰混凝土的蠕變特征曲線、峰值應(yīng)力、峰值應(yīng)變、蠕變變形模量、蠕變速率、表觀凍融形貌和宏觀破壞特征隨凍融次數(shù)的變化規(guī)律。(3)借助掃描電鏡測試手段,發(fā)現(xiàn)了單孔、不連通孔洞簇、連通孔洞簇和粉煤灰孔洞四種孔洞形貌特征,河流花、臺階花、層疊花、半球面花、不規(guī)則花五種脆性斷裂特征和韌窩、峰林兩種韌性斷裂特征,得到了混凝土微細觀孔結(jié)構(gòu)和斷口形貌特征隨粉煤灰摻量和凍融次數(shù)的變化規(guī)律。(4)基于材料流變力學和損傷力學理論,建立了非線性粘彈塑性流變力學模型(MSSB-NVPB和孫鈞-NVPB模型),分別用于描述未凍融和凍融時粉煤灰混凝土的流變特性,推導了對應(yīng)的本構(gòu)方程、蠕變方程、卸載方程和松弛方程,結(jié)合粉煤灰混凝土凍融蠕變加卸載試驗數(shù)據(jù),求解了模型參數(shù),分析了其與粉煤灰摻量和凍融次數(shù)的變化規(guī)律,模型理論值與試驗值吻合較好。(5)建立了粉煤灰摻量m和凍融次數(shù)n的混凝土損傷演化方程;提出了考慮損傷的非線性粘彈塑性蠕變損傷模型,推導出了其相對應(yīng)的損傷蠕變方程。
[Abstract]:As China's western development, the revitalization of northeast old industrial zone, "the implementation of The Belt and Road" strategy, many large concrete structure engineering construction started quickly, this kind of project to play an important role in people's life and economic development, but the harsh environmental conditions so life is greatly reduced, the freezing thawing hazards on environment the concrete structure has brought great economic loss to the country. The freeze-thaw damage of concrete creep and rupture mechanism of environment is the basis to solve the durability problem of this kind of engineering. In this paper, the fly ash concrete as the research object, with the help of KDS-60 rapid freeze-thaw test machine, computer controlled electro-hydraulic servo system and other modern test creep test technical analysis, comprehensive application of theory, methods and means of experimental research, the general mechanical properties of freezing, thawing after fly ash concrete creep characteristics, macro fracture characteristics, micro The concept of pore structure and fracture characteristics, the theory of rheological model, freeze-thaw damage creep fracture mechanism were studied. The main research results are as follows: (1) by rapid freezing and thawing of the electro-hydraulic servo control system test and creep test of high-strength concrete on the computer, not adding fly ash to freeze-thaw of creep test, the creep curve, peak stress, peak strain, elastic modulus, creep deformation modulus, instantaneous strain, creep rate, rupture characteristics of macro variations with the number of freeze-thaw cycles. (2) system for the determination of creep properties of fly ash concrete and freeze-thaw creep, creep modulus is obtained and the variation of the creep rate such as the amount of fly ash, the creep characteristic curve of fly ash concrete, peak stress, peak strain, creep deformation modulus, creep rate, apparent morphology and freeze-thaw macrocharacters with freezing Changes of the number of freeze-thaw. (3) by scanning electron microscopy test means, found a single hole, not connected hole cluster, connected hole cluster and fly ash hole four hole river morphology, flower, flower flower stage, stacked, hemispherical flowers, irregular flowers five brittle fracture and dimple, two characteristic peaks of ductile fracture, the concrete micro pore structure and fracture morphology with fly ash and variation of freeze-thaw cycles. (4) the rheological mechanics and material based on the theory of damage mechanics, the nonlinear viscoelastic plastic rheological model (MSSB-NVPB and Sun Jun -NVPB model), which are used to describe not the rheological properties of fly ash concrete freezing and thawing, constitutive equation, the corresponding deduced creep equation, unloading equation and the relaxation equation, combined with fly ash concrete freeze-thaw creep loading and unloading test data, solving the parameters of the model, and its analysis Fly ash and freeze thawing times changes, the model theoretical value is in good agreement with the experimental results. (5) the establishment of the fly ash concrete damage evolution equation m and freeze thawing times of N; the damage of nonlinear viscoelastic plastic creep damage model considering creep damage equation was deduced by the the corresponding.

【學位授予單位】：中國礦業(yè)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TU528
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本文編號：1686809