严寒地区桥梁结构高性能混凝土耐久性研究

发布时间：2018-07-12 15:41

本文选题：严寒地区 + 桥梁结构高性能混凝土　；参考：《吉林大学》2017年硕士论文

【摘要】：在严寒地区,桥梁结构在冻融环境下的耐久性十分重要,直接影响桥梁使用寿命期限,而现在的桥梁依旧采用较为传统的普通混凝土进行修建,经常出现冻融破坏现象。本文依托寒区路桥隧高性能混凝土施工质量控制技术研究项目,提出通过掺加硅藻土类材料的方法来提高桥梁结构混凝土在严寒地区的耐久性。在理论上分析冻融环境下混凝土的耐久性。从混凝土孔结构和结冰规律出发,利用静水压理论和渗透压理论来研究混凝土在冻融环境下耐久性变化机理。根据混凝土在冻融环境下的损伤规律,将损伤理论作为建立混凝土耐久模型的框架。研究影响混凝土抗冻性的主要因素,即混凝土的水胶比、含气量、粗集料和掺合料,并具体分析这些因素对混凝土抗冻性的影响机理。在满足实际工程要求的桥梁结构混凝土配合比基础上,考虑冻融环境下混凝土耐久性的影响因素,提出抗冻试验配合比,并进行混凝土抗冻性的相关试验,分析研究在冻融作用下普通桥梁结构混凝土的耐久性,探究三种标号混凝土的外观损伤、质量损失和相对动弹性模量变化规律,总结引气剂掺量、粉煤灰掺量和水胶比对变化规律的影响。综合理论与试验结果研究普通桥梁结构混凝土在冻融作用下的耐久性。开展冻融作用下掺加硅藻土类材料桥梁结构混凝土的耐久性试验,在普通桥梁结构混凝土中分别掺入不同量的硅藻土和煅烧硅藻土,对比其与普通混凝土在工作性能、强度和抗渗等级方面的差异性。从混凝土外观损伤、质量损失和相对动弹性模量等方面,来进行不同掺量的硅藻土、煅烧硅藻土和普通混凝土三者抗冻性的分析,并以抗冻损伤度为指标,定量评价抗冻性的大小。分析掺加硅藻土类材料混凝土抗冻性提高的机理,应用损伤理论和威布尔分布建立混凝土在冻融作用下的损伤模型,利用MATLAB通过图解法模拟在不同采集时间的截面等效图,对比分析普通混凝土和掺加硅藻土混凝土在相同采样时间截面的破坏规律。综合理论、试验和模型完整的研究严寒地区桥梁结构高性能混凝土的耐久性。
[Abstract]:The durability of bridge structure in freezing and thawing environment is very important in severe cold area, which directly affects the service life of bridge, but the bridge is still constructed with conventional concrete, which often occurs freeze-thaw damage. Based on the research project of high performance concrete construction quality control in cold region, this paper puts forward the method of adding diatomite material to improve the durability of bridge structure concrete in cold area. The durability of concrete in freeze-thaw environment is analyzed theoretically. Based on the pore structure of concrete and the rule of ice formation, the mechanism of durability of concrete under freeze-thaw environment is studied by using hydrostatic pressure theory and osmotic pressure theory. According to the damage law of concrete in freeze-thaw environment, the damage theory is used as the frame to establish concrete durability model. This paper studies the main factors affecting the frost resistance of concrete, that is, the water-binder ratio, air content, coarse aggregate and admixture of concrete, and analyzes the influence mechanism of these factors on the frost resistance of concrete. On the basis of concrete mix ratio of bridge structure which meets the requirements of practical engineering, considering the influence factors of concrete durability under freeze-thaw environment, the mixture ratio of frost resistance test is put forward, and the relevant test of concrete frost resistance is carried out. The durability of common bridge structure concrete under the action of freeze-thaw is analyzed, the appearance damage, mass loss and relative dynamic elastic modulus of three kinds of graded concrete are studied, and the amount of air entraining agent is summarized. The effect of fly ash content and water / binder ratio on the change of fly ash content. The durability of common bridge structure concrete under freeze-thaw action is studied by synthesizing the theoretical and experimental results. The durability test of bridge structure concrete mixed with diatomite material under freezing and thawing is carried out. Different amounts of diatomite and calcined diatomite are mixed in ordinary bridge structure concrete respectively, and the performance of the concrete is compared with that of ordinary concrete. Differences in strength and impermeability grades. From the aspects of concrete appearance damage, mass loss and relative dynamic elastic modulus, the frost resistance of diatomite, calcined diatomite and ordinary concrete is analyzed, and the degree of frost damage is taken as the index. The degree of frost resistance was evaluated quantitatively. This paper analyzes the mechanism of improving the frost resistance of concrete with diatomite material, establishes the damage model of concrete under freeze-thaw by using damage theory and Weibull distribution, and simulates the equivalent section diagram of concrete collected at different time by means of MATLAB graphic method. The failure law of ordinary concrete and diatomite concrete in the same sampling time section is analyzed. The durability of high performance concrete (HPC) of bridge structure in severe cold area is studied by comprehensive theory, test and model.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U444

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