本文選題：預應力混凝土　切入點：氯離子　出處：《長沙理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：預應力混凝土結(jié)構(gòu)具有性能好、跨度大的特點,在我國土木、水利與交通工程等領(lǐng)域得到了廣泛應用。然而大量工程實踐表明預應力混凝土結(jié)構(gòu)在長期使用過程中會由于許多預料不到的原由從而致使結(jié)構(gòu)功能退化,導致服務年限不能達到目標年限。這其中主要原因就是由于鋼筋銹蝕,而對鋼筋銹蝕影響最大就是氯離子侵蝕。文章研究了壓應力狀態(tài)下混凝土的氯離子侵蝕問題,進行了人工氣候環(huán)境下氯離子侵入混凝土的試驗。試驗考慮了水灰比與應力水平兩種因素,設(shè)計了三種不同的水灰比與應力狀態(tài)。本文所做的工作及研究內(nèi)容如下:(1)設(shè)計人工氣候環(huán)境下無應力與壓應力狀態(tài)下混凝土進行氯鹽噴霧試驗,記錄并分析試驗數(shù)據(jù)。(2)基于Fick第二定律,綜合考慮了預應力、溫度、混凝土氯離子結(jié)合能力、氯離子擴散系數(shù)的時間依賴性和結(jié)構(gòu)缺陷等多方面因素的影響,建立了多因素作用下預應力混凝土的氯離子擴散模型。(3)通過對試驗數(shù)據(jù)分析發(fā)現(xiàn)不同水灰比的混凝土在人工氣候環(huán)境下,低水灰比的混凝土會比高水灰比的在抵抗氯離子侵入這一方面要提高一定比例�；炷猎诔惺軌簯r會對在其內(nèi)的氯離子擴散有較為大影響,同一水灰比的混凝土在不同的應力狀態(tài)下,氯離子在其中的擴散隨壓應力的逐漸增大而擴散速率降低。(4)通過本次試驗的數(shù)據(jù)對本文研究的氯離子擴散模型進行了驗證,驗證結(jié)果表明此擴散模型有較好的適用性,為氯鹽環(huán)境下的預應力混凝土結(jié)構(gòu)耐久性研究提供了理論依據(jù)。(5)分析了初銹模型的影響因素,研究發(fā)現(xiàn)基本參數(shù)的服從的概率密度函數(shù)各不相同。對初銹時間模型進行了敏感性分析,研究發(fā)現(xiàn)初銹模型對這些參數(shù)的敏感性程度也各不相同,其中對保護層厚度敏感性最強,其次是臨界濃度,而對擴散系數(shù)敏感性次之,其對表面濃度與應力水平最低。
[Abstract]:Prestressed concrete structure has the characteristics of good performance and large span. The field of water conservancy and traffic engineering has been widely used. However, a large number of engineering practices have shown that the function of prestressed concrete structures will degenerate due to many unexpected original reasons during their long-term use. The main reason is that the corrosion of steel bar is the main reason, and the corrosion of chloride ion is the most important influence on the corrosion of steel bar. In this paper, the problem of chloride ion erosion in concrete under compressive stress is studied. The experiment of chloride ion intrusion into concrete in artificial climate was carried out. Two factors, water-cement ratio and stress level, were taken into account in the experiment. Three different water-cement ratio and stress states are designed. The work and research contents in this paper are as follows: (1) the chlorine spray test of concrete under the condition of no stress and compressive stress in artificial climate is designed. Based on the second law of Fick, the influences of prestress, temperature, chloride binding capacity of concrete, time dependence of chloride diffusion coefficient and structural defects are comprehensively considered. The chloride diffusion model of prestressed concrete under multi-factor action is established. By analyzing the experimental data, it is found that the concrete with different water-cement ratio is in artificial climate. The concrete with low water-cement ratio will increase its resistance to chloride ion intrusion by a certain proportion than the concrete with high water-cement ratio. When the concrete is subjected to compressive stress, it will have a greater influence on the chloride ion diffusion in the concrete. Under different stress states of concrete with the same water-cement ratio, the diffusion rate of chloride ions decreases with the increasing of compressive stress. The results show that the diffusion model has good applicability and provides a theoretical basis for the durability study of prestressed concrete structures under chloride environment. It is found that the probability density function of the basic parameters is different. The sensitivity of the initial rust time model is analyzed, and the sensitivity of the initial rust model to these parameters is also different. The thickness of the protective layer is the most sensitive, followed by the critical concentration, the second is the diffusion coefficient, and the lowest is the surface concentration and stress level.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU378

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本文編號：1557438