【摘要】：混凝土的耐久性退化影響結(jié)構(gòu)服役的可靠性和安全性,產(chǎn)生這種影響的原因是由于混凝土結(jié)構(gòu)的服役壽命縮短。尤其是硫酸鹽侵蝕混凝土的過程是一個包含物理、化學(xué)、力學(xué)等多方面作用效應(yīng)的繁雜現(xiàn)象,其影響的因素繁多、損傷較大,是混凝土耐久性探究的重要內(nèi)容之一。 實際工程中,當(dāng)混凝土受到荷載因素與環(huán)境因素耦合作用時,其作用機(jī)理更為復(fù)雜。因此開展力學(xué)與鹽溶液耦合作用下混凝上耐久性研究對預(yù)測其服役壽命的合理性與提高混凝土結(jié)構(gòu)設(shè)計的安全性具有重要的理論意義和應(yīng)用價值。同時從硫酸根離子擴(kuò)散角度對研究混凝土耐久性工作進(jìn)行綜合評定,為長時間處于硫酸鹽環(huán)境下的混凝土耐久性設(shè)計提供基礎(chǔ)的理論依據(jù)。為此本文針對混凝土在硫酸鹽、氯鹽和荷載耦合作用下的損傷進(jìn)行研究,此外,還開展了硫酸鹽侵蝕作用下擴(kuò)散規(guī)律的數(shù)值分析,并最終建立壽命預(yù)測模型。主要研究工作如下： (1)首先研究了混凝土在單因素(硫酸鹽)、雙因素(氯鹽、硫酸鹽)、三因素(彎曲荷載、氯鹽、硫酸鹽)下?lián)p傷演化規(guī)律,分析不同因素作用下混凝土動彈性模量的變化規(guī)律及復(fù)合因素對相對動彈性模量的影響規(guī)律。利用相對動彈性模量建立考慮力學(xué)因素、環(huán)境因素以及材料因素對混凝土損傷失效演化方程。 (2)其次探討了鋼筋混凝土在硫酸鹽、氯鹽和荷載耦合因素作用下的鋼筋銹蝕和損傷演化規(guī)律。分析不同因素作用下鋼筋腐蝕電位、腐蝕電流密度隨著時間推移而變化,且會隨著混凝土水灰比的不同及荷載率的不同而發(fā)生變化。鋼筋混凝土動彈性模量變化會受到壓應(yīng)力作用而損傷進(jìn)程延緩,同時拉應(yīng)力則會加速損傷進(jìn)程,但荷載的存在不會改變混凝土的損傷演化規(guī)律。 (3)再者利用實驗研究了各個強(qiáng)度等級混凝土在復(fù)合溶液中離子擴(kuò)散分布規(guī)律,研究了硫酸鹽溶液中硫酸根離子在各水灰比下混凝土的離子擴(kuò)散規(guī)律,并考慮了復(fù)合溶液中氯離子存在對硫酸根離子擴(kuò)散分布規(guī)律的影響。同時研究了氯鹽溶液中自由氯離子和總氯離子在各水灰比下混凝土的離子擴(kuò)散規(guī)律,并考慮了復(fù)合溶液中硫酸根離子存在對自由氯離子和總氯離子擴(kuò)散分布規(guī)律的影響。 (4)最后研究了硫酸根離子在混凝土中的擴(kuò)散模型,并通過硫酸根離子的擴(kuò)散模型對混凝土進(jìn)行了壽命預(yù)測。不僅建立了硫酸根離子擴(kuò)散系數(shù)隨著時間衰減的規(guī)律；還建立了硫酸根離子擴(kuò)散系數(shù)與混凝土損傷的相對動彈性模量的關(guān)系；并建立了氯離子結(jié)合能力對硫酸根離子擴(kuò)散系數(shù)的修正關(guān)系。
[Abstract]:The durability degradation of concrete affects the reliability and safety of the structure, which is due to the shortened service life of the concrete structure. The process of sulfate erosion on concrete is a complicated phenomenon which includes many effects such as physics, chemistry and mechanics. The factors affecting concrete are many and the damage is great. It is one of the important contents of concrete durability research. In practical engineering, the action mechanism of concrete is more complicated when it is coupled by load factors and environmental factors. Therefore, the study on the durability of coagulation under the coupling of mechanics and salt solution is of great theoretical significance and application value in predicting the rationality of service life and improving the safety of concrete structure design. At the same time, the durability of concrete is evaluated comprehensively from the angle of sulfate ion diffusion, which provides the theoretical basis for the durability design of concrete in sulfate environment for a long time. In this paper, the damage of concrete under the coupling action of sulfate, chloride and load is studied. In addition, the numerical analysis of diffusion law under sulfate erosion is carried out, and finally the life prediction model is established. The main research work is as follows: (1) the damage evolution of concrete under single factor (sulfate), double factor (chloride salt, sulfate) and three factors (bending load, chloride salt, sulfate) is studied. The variation of dynamic elastic modulus of concrete under the action of different factors and the influence of compound factors on relative dynamic elastic modulus of concrete are analyzed. Based on the relative dynamic elastic modulus, the evolution equation of damage failure of concrete considering mechanical factors, environmental factors and material factors is established. (2) secondly, the corrosion and damage evolution of reinforced concrete under the action of sulfate, chlorate and load coupling factors are discussed. The corrosion potential of steel bars under different factors is analyzed. The corrosion current density changes with the passage of time. The corrosion current density changes with the different water-cement ratio of concrete and the different loading rate. The change of dynamic elastic modulus of reinforced concrete will be delayed by compressive stress, and the damage process will be accelerated by tensile stress. However, the existence of load will not change the damage evolution of concrete. (3) the distribution of ion diffusion of concrete of different strength grades in composite solution is studied by experiment, and the law of ion diffusion of sulfate ion in each water-cement ratio of concrete in sulfate solution is studied. The influence of chloride ion in complex solution on the diffusion distribution of sulfate ion was also considered. At the same time, the ion diffusion law of free chloride ion and total chloride ion in chloride solution under different water-cement ratios was studied, and the influence of sulfate ion in compound solution on the diffusion distribution of free chloride ion and total chloride ion was considered. (4) finally, the diffusion model of sulfate ion in concrete is studied, and the life of concrete is predicted by the diffusion model of sulfate ion. The relationship between the diffusion coefficient of sulfate ion and the relative dynamic elastic modulus of concrete damage is also established, and the relationship between the diffusion coefficient of sulfate ion and the relative dynamic elastic modulus of concrete damage is also established. The correction relationship between chloride binding capacity and diffusion coefficient of sulfate ion was established.
【學(xué)位授予單位】：揚(yáng)州大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU528

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