海洋环境下混凝土的氯离子传输模型研究

发布时间：2018-05-20 12:06

  本文选题：海洋环境 + 耐久性　； 参考：《天津大学》2014年硕士论文

【摘要】：通过调查研究,海洋环境下的许多混凝土结构在还没有达到预定的服役寿命前,就需要耗费大量的资金对其进行修护或重建,究其主要原因是多种海洋环境要素的共同作用加速了海水中氯离子在混凝土中侵蚀,导致钢筋发生电化学腐蚀。目前,对于混凝土耐久性的研究仍处于经验阶段,干湿交替作用下的氯离子传输模型研究尚不完善。本文在综合分析已有成果的基础上,以氯离子传输机理为中心,建立了在材料性质和环境要素的影响下,适用于海洋环境的氯离子传输模型。并且以江苏东海海域的海上风电场为工程背景,通过理论研究和数值分析,研究了处于水位变动区的基础薄壁结构的氯离子侵蚀规律,具体内容如下:1、分析混凝土结构耐久性破坏的机理,研究影响氯离子传输和钢筋腐蚀的材料性质,其中水灰比和保护层厚度是影响结构寿命最关键的材料因素。2、将海洋环境多因素作用下的氯离子传输过程分解为温度传导、水分传输、氯离子扩散和对流几个子过程,分析各子过程的运行机理、计算公式、发生条件和相互之间耦合作用,建立海洋环境下的氯离子传输模型。3、考虑太阳辐射和潮汐水位变动等因素影响下边界条件的变化,利用有限差分方法对全寿命周期的温度场、湿度场、氯离子浓度场进行数值模拟分析,分析日照效应和干湿循环对氯离子传输的加速作用。4、应用本模型分析氯离子侵蚀随地理位置、朝向、高程的分布规律。位于低纬度地区的结构日照能量吸收量是高纬度的3.08倍,朝阳面的平均温度比朝阴面高2.9℃,对流区的氯离子浓度随高程升高呈先增大后减小的变化趋势。5、对江苏某海上风电混凝土基础结构进行耐久性评估,分析其各物理场的变化规律,并提出相应的改善措施。
[Abstract]:Through investigation and research, many concrete structures in the marine environment need to spend a lot of money to repair or rebuild them before they reach their scheduled service life. The main reason is that the combined action of various marine environmental elements accelerates the corrosion of chloride ions in seawater and leads to electrochemical corrosion of steel bars. At present, the research on concrete durability is still in the experience stage, and the chloride transport model under the alternating action of dry and wet is not perfect. In this paper, based on the comprehensive analysis of the existing achievements and focusing on the mechanism of chloride ion transport, a chloride transport model suitable for marine environment is established under the influence of material properties and environmental factors. Taking the offshore wind farm in the East China Sea of Jiangsu Province as the engineering background, through theoretical research and numerical analysis, the chloride ion erosion law of the thin-walled foundation structure in the water level changing area is studied. The specific contents are as follows: 1. Analyze the mechanism of durability failure of concrete structures, study the properties of materials that affect chloride ion transport and corrosion of steel bars. The water-cement ratio and the thickness of the protective layer are the most important material factors affecting the life of the structure. The chlorine ion transport process under the action of many factors in the marine environment is decomposed into several sub-processes, such as temperature conduction, water transport, chloride ion diffusion and convection. The operation mechanism, calculation formula, occurrence condition and coupling action of each sub-process are analyzed, and the chlorine ion transport model .3 in marine environment is established. The variation of boundary conditions under the influence of solar radiation and tidal water level is taken into account. The finite difference method is used to simulate the temperature field, humidity field and chloride concentration field in the whole life cycle. The effect of sunlight and the accelerated effect of dry and wet cycle on chloride ion transport were analyzed. The distribution of chloride ion erosion with geographical location, orientation and elevation was analyzed by using this model. The solar energy absorption of the structure located in the low latitude is 3.08 times of that of the high latitude, and the average temperature of the morning sun is 2.9 鈩，

本文编号：1914557