隧道混凝土多因素定向腐蚀效应与性能退化规律研究

发布时间：2018-03-13 16:25

本文选题：氯盐　切入点：硫酸盐　出处：《江苏科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：岩体隧道广泛存在于我国各个地区,对穿越障碍缩短行车里程缓解交通压力做出巨大贡献,但其耐久性问题日益突出。对隧道混凝土耐久性影响最大的是硫酸盐腐蚀,在绝大部分环境水中同时存在氯盐与硫酸盐相互作用。双因素(硫酸盐与氯盐复合作用)腐蚀环境下岩体隧道衬砌的侵蚀效应与同样环境下软土隧道侵蚀效应相比具有明显的不同,与单因素(氯盐与硫酸盐单独作用)腐蚀环境下隧道衬砌的侵蚀效应也有很大不同,同时隧道混凝土也受到碳化作用的侵蚀。本文针对隧道环境的实际情况,考虑多种因素(硫酸盐氯盐碳化)耦合作用,研究隧道混凝土单向侵蚀效应及退化规律。本文对混凝土单方向半浸泡腐蚀进行研究,在自然环境下锈蚀钢筋,考虑不同腐蚀环境,即Na2SO4溶液(浓度为5%10%)与NaCl溶液(浓度为5%10%)之间相互组合以及碳化作用,分析多种因素耦合作用下隧道钢筋混凝土的腐蚀性能退化规律,并对退化原因做出相应的分析。(1)通过对纯Na_2SO_4溶液与NaClNa2SO4混合溶液环境中腐蚀的混凝土试块进行超声声速测量,运用公式计算出各组混凝土试块的腐蚀层厚度,用以评价氯盐对硫酸盐腐蚀混凝土的抑制作用,并进行XRD衍射分析及电镜扫描。实验结果表明:通过对腐蚀层厚度变化的比较及微观形态的观察,都证实了Cl-的存在抑制了SO_4~(2-)对混凝土的腐蚀作用,并且随着Cl-浓度增加抑制效果有一定程度增强。(2)研究碳化对双因素腐蚀混凝土中SO_4~(2-)的扩散影响,以及在多因素条件下混凝土力学性能和耐久性的变化规律。通过测量不同工况条件下,混凝土各深度SO_4~(2-)的浓度,研究SO_4~(2-)在混凝土中的扩散规律,以及不同浓度情况下Cl-对SO_4~(2-)扩散的影响,进一步探究多因素条件下SO_4~(2-)对混凝土的腐蚀情况。结果表明:碳化促进了SO_4~(2-)的扩散速度,加剧了混凝土的腐蚀程度;多因素(碳化Cl-SO_4~(2-))对混凝土的腐蚀作用,碳化主要起促进作用,Cl-起抑制作用,各种复杂因素的耦合作用还有待进一步研究。(3)研究在氯盐硫酸盐双因素耦合作用下,混凝土中钢筋的腐蚀规律,主要对钢筋锈蚀率和不同锈蚀率钢筋抗拉性能的测定。结果表明:SO_4~(2-)的存在可以减轻Cl-对钢筋的锈蚀,对抗拉性能也有一定影响。
[Abstract]:Rock mass tunnel exists widely in every area of our country. Shorter mileage? Traffic pressure relief has made a great contribution, but the durability problem is becoming increasingly prominent. The most important impact on the durability of tunnel concrete is sulphate corrosion. In most of the environmental water, the interaction of chloride and sulfate exists simultaneously. The corrosion effect of tunnel lining in rock mass under the condition of double factors (sulfate and chloride compound interaction) is similar to that of tunnel in soft soil in the same environment. Is obviously different, The corrosion effect of tunnel lining is different from that of single factor (chloride and sulfate alone), and the concrete of tunnel is also corroded by carbonization. Consider a variety of factors (sulfate? Chloride? In this paper, the unidirectional and semi-immersion corrosion of concrete in one direction is studied. In the natural environment, corrosion of steel bars is considered in different corrosion environments, that is, Na2SO4 solution (concentration 5? 10) and NaCl solution (concentration 5? The corrosion degradation law of tunnel reinforced concrete under the coupling action of various factors is analyzed, and the corresponding analysis of degradation cause is made. 1) through the analysis of pure Na_2SO_4 solution and NaCl-NaCl-1, the corrosion behavior of tunnel reinforced concrete under the coupling of various factors is analyzed by combining and carbonizing each other. The ultrasonic sound velocity measurement was carried out on the concrete samples corroded in the environment of Na2SO4 mixed solution. The thickness of corrosion layer of each group of concrete samples was calculated by using the formula to evaluate the inhibition effect of chloride salt on sulphate corroded concrete. The results of XRD diffraction and scanning electron microscopy show that the existence of Cl- inhibits the corrosion of concrete by comparing the thickness of corrosion layer and observing the microstructure of the corrosion layer. The effect of carbonation on the diffusion of so _ 4 / C _ 2 in double-factor corroded concrete was studied with the increase of Cl-concentration. And the variation law of mechanical properties and durability of concrete under multi-factor conditions. By measuring the concentration of so _ 4 / C _ 2 in different depths of concrete under different working conditions, the diffusion law of so _ 4 / C _ 2) in concrete is studied. And the effect of Cl-on SO4C2-diffusion at different concentrations, and further study on the corrosion of concrete under multi-factor conditions. The results show that carbonization promotes the diffusion rate of SO4C2-and intensifies the corrosion degree of concrete. Cl-? Carbonation plays an important role in inhibiting the corrosion of concrete. The coupling of various complex factors needs to be further studied. Under the coupling of sulfate with two factors, the corrosion law of steel bars in concrete is mainly determined on the corrosion rate of steel bars and the tensile properties of steel bars with different corrosion rates. The results show that the presence of 1 / so _ 4 / 2) can reduce the corrosion of steel bars by Cl-. Tensile resistance also has a certain impact on the performance.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U454

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