【摘要】：本論文針對耐久性問題最為突出的海港工程混凝土結(jié)構(gòu),通過對我國具有代表性的實際海港工程混凝土結(jié)構(gòu)服役期應(yīng)力水平測試與分析,獲得典型構(gòu)件在實際服役環(huán)境中的荷載類型和具有代表性的荷載水平范圍；采用自主開發(fā)的恒定加壓載荷和彎曲載荷裝置,以工程實際的荷載類型和荷載水平為基礎(chǔ),從壓／彎曲等靜荷載類型、施加載荷范圍、混凝土摻合料種類及摻量、混凝土配比參數(shù)等方面,通過室內(nèi)海水模擬試驗箱的人工加速模擬試驗方法以及混凝土結(jié)構(gòu)微觀測試手段,開展處于“荷載+氯鹽”條件下和“荷載+氯鹽+凍融”作用下的海港工程混凝土結(jié)構(gòu)氯離子擴散行為的研究。得出以下主要結(jié)論：(1)數(shù)值模擬、理論計算和現(xiàn)場實際測試與分析表明：所研究的海港工程混凝土構(gòu)件服役期的實際應(yīng)力水平有限元分析基本在7%-50%范圍；“永久荷載+可變荷載”應(yīng)力水平約在30%-40%之間。(2)混凝土氯離子擴散系數(shù)與彎曲應(yīng)力水平間呈指數(shù)函數(shù)關(guān)系,可用公式Y(jié)=A·eBx進行表述。對于摻入活性礦物摻合料的海工高性能混凝土,其氯離子擴散系數(shù)的恒定彎曲荷載作用影響因子表達式為：Dη=0.9769·D0·e1.363η;彎曲荷載和凍融共同作用影響因子表達式為：Ddη=1.0224·D0·e1.6383η。(式中,η為自變量應(yīng)力水平,Do為無荷載混凝土的氯離子擴散系數(shù),Ddη、Dη為應(yīng)力水平為η時混凝土的氯離子擴散系數(shù)。)(3)混凝土氯離子擴散系數(shù)隨著壓應(yīng)力的增加呈現(xiàn)先降低后增高的趨勢,所研究的混凝土約施加應(yīng)力水平為30%時最低；壓應(yīng)力單獨作用下,應(yīng)力水平為η混凝土的氯離子擴散系數(shù)D。與無荷載時混凝土氯離子擴散系數(shù)D0關(guān)系式為：(4)基于室內(nèi)的研究成果,對以可靠度理論為基礎(chǔ)而建立的海工混凝土結(jié)構(gòu)耐久性壽命預(yù)測模型中的關(guān)鍵參數(shù)進行了考慮恒定彎曲荷載作用的修正,建立了恒定彎曲荷載作用下海工混凝土結(jié)構(gòu)耐久性壽命預(yù)測模型：(5)鹽凍條件下,混凝土的相對動彈模量隨凍融循環(huán)次數(shù)的增加而降低；混凝土的質(zhì)量損失率隨凍融循環(huán)次數(shù)的增加而增加,混凝土的質(zhì)量損失率還隨承受彎曲荷載應(yīng)力水平的提高而增大。(6)彎曲荷載與凍融共同作用和彎曲荷載單獨作用都會引起混凝土孔隙結(jié)構(gòu)的變化,提高應(yīng)力水平不僅會提高混凝土的平均孔徑和總孔體積,還改變了混凝土的孔徑分布。荷載與凍融共同作用對混凝土孔隙結(jié)構(gòu)的影響要大于荷載單獨作用對混凝土孔隙結(jié)構(gòu)的影響,孔隙結(jié)構(gòu)變化是引起氯離子擴散系數(shù)變化的主要因素。
[Abstract]:In this paper, the concrete structure of seaport engineering, which is the most prominent durability problem, is tested and analyzed by testing and analyzing the stress level of concrete structure of practical seaport engineering, which is representative of our country. The load type and the representative load level range of the typical members in the actual service environment are obtained. Based on the actual load type and load level of the project, the static load types such as compression / bending, the range of load applied, the type and the amount of concrete admixture are adopted by the self-developed constant load and bending load device, which is based on the actual load type and load level of the project. In the aspects of concrete proportioning parameters, the artificial accelerated simulation test method of indoor seawater simulation test box and the micro-testing method of concrete structure are adopted. The diffusion behavior of chloride ions in concrete structures of harbour engineering under the condition of "load chloride salt" and "freeze-thaw of load chloride salt" was studied. The main conclusions are as follows: (1) numerical simulation, theoretical calculation and field test and analysis show that the actual stress level finite element analysis of concrete members in seaport engineering is basically in the range of 7% to 50%; The stress level of "permanent load variable load" is about 30% ~ 40%. (2) there is an exponential function relationship between chloride diffusion coefficient and bending stress level, which can be expressed by formula Y = A 路eBx. For marine high performance concrete mixed with active mineral admixture, the influence factor of chloride diffusion coefficient under constant bending load is expressed as follows: d 畏 = 0.9769 路D 0 路e 1.363 畏; The expression of Dd 畏 = 1.0224 路D _ 0 路e _ 1. 6383 畏 for the interaction of bending load and freezing-thawing. (here, 畏 is the stress level of independent variables, and Do is the chloride diffusion coefficient of unloaded concrete, Dd 畏, When the stress level is 畏, the chloride diffusion coefficient of concrete.) (3) the chloride diffusion coefficient of concrete decreases at first and then increases with the increase of compressive stress, and the applied stress level of the concrete studied is the lowest when the applied stress level is about 30%. Under the action of compressive stress alone, the stress level is the chloride diffusion coefficient of 畏 concrete. The formula of chloride diffusion coefficient D _ 0 between concrete and concrete without load is as follows: (4) based on the research results in laboratory, The key parameters in the durability life prediction model of marine concrete structures based on reliability theory are modified considering the action of constant bending load. The durability life prediction model of marine concrete structure under constant bending load is established: (5) under salt freezing condition, the relative dynamic elastic modulus of concrete decreases with the increase of freezing and thawing cycles; The mass loss rate of concrete increases with the increase of freezing and thawing cycles. The mass loss rate of concrete also increases with the increase of bending load stress level. (6) the interaction of bending load with freeze-thaw and bending load alone will cause the change of concrete pore structure. Increasing the stress level will not only increase the average pore size and total pore volume of concrete, but also change the pore size distribution of concrete. The influence of the interaction of load and freeze-thaw on concrete pore structure is greater than that of concrete pore structure by load alone. The change of pore structure is the main factor that causes the change of chloride ion diffusion coefficient.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TV33

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