荷载与盐溶液耦合作用下混凝土耐久性与寿命预测
发布时间：2019-04-26 06:11
【摘要】：混凝土的耐久性退化影响结构服役的可靠性和安全性,产生这种影响的原因是由于混凝土结构的服役寿命缩短。尤其是硫酸盐侵蚀混凝土的过程是一个包含物理、化学、力学等多方面作用效应的繁杂现象,其影响的因素繁多、损伤较大,是混凝土耐久性探究的重要内容之一。 实际工程中,当混凝土受到荷载因素与环境因素耦合作用时,其作用机理更为复杂。因此开展力学与盐溶液耦合作用下混凝上耐久性研究对预测其服役寿命的合理性与提高混凝土结构设计的安全性具有重要的理论意义和应用价值。同时从硫酸根离子扩散角度对研究混凝土耐久性工作进行综合评定,为长时间处于硫酸盐环境下的混凝土耐久性设计提供基础的理论依据。为此本文针对混凝土在硫酸盐、氯盐和荷载耦合作用下的损伤进行研究,此外,还开展了硫酸盐侵蚀作用下扩散规律的数值分析,并最终建立寿命预测模型。主要研究工作如下： (1)首先研究了混凝土在单因素(硫酸盐)、双因素(氯盐、硫酸盐)、三因素(弯曲荷载、氯盐、硫酸盐)下损伤演化规律,分析不同因素作用下混凝土动弹性模量的变化规律及复合因素对相对动弹性模量的影响规律。利用相对动弹性模量建立考虑力学因素、环境因素以及材料因素对混凝土损伤失效演化方程。 (2)其次探讨了钢筋混凝土在硫酸盐、氯盐和荷载耦合因素作用下的钢筋锈蚀和损伤演化规律。分析不同因素作用下钢筋腐蚀电位、腐蚀电流密度随着时间推移而变化,且会随着混凝土水灰比的不同及荷载率的不同而发生变化。钢筋混凝土动弹性模量变化会受到压应力作用而损伤进程延缓,同时拉应力则会加速损伤进程,但荷载的存在不会改变混凝土的损伤演化规律。 (3)再者利用实验研究了各个强度等级混凝土在复合溶液中离子扩散分布规律,研究了硫酸盐溶液中硫酸根离子在各水灰比下混凝土的离子扩散规律,并考虑了复合溶液中氯离子存在对硫酸根离子扩散分布规律的影响。同时研究了氯盐溶液中自由氯离子和总氯离子在各水灰比下混凝土的离子扩散规律,并考虑了复合溶液中硫酸根离子存在对自由氯离子和总氯离子扩散分布规律的影响。 (4)最后研究了硫酸根离子在混凝土中的扩散模型,并通过硫酸根离子的扩散模型对混凝土进行了寿命预测。不仅建立了硫酸根离子扩散系数随着时间衰减的规律；还建立了硫酸根离子扩散系数与混凝土损伤的相对动弹性模量的关系；并建立了氯离子结合能力对硫酸根离子扩散系数的修正关系。
[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.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528
本文编号：2465822
[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.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528
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