【作者】 陈静；

【导师】 杜应吉；

【作者基本信息】 西北农林科技大学 ， 水利水电工程， 2009， 硕士

【摘要】 混凝土在硫酸盐侵蚀、氯离子渗透、碳化等因素影响下的耐久性研究,已成为国内外工程界研究的热点问题。本文主要针对其中两个问题进行了研究。其一,对于硫酸盐侵蚀下混凝土的损伤研究,虽然国内外己经做了一些混凝土的试验研究,得出了一些混凝土抗硫酸盐侵蚀的模型,但多为经验模型,大部分试验研究未能反映混凝土在硫酸盐作用下的损伤全过程,且尚无公认的能快速而精确的预测混凝土抗硫酸盐侵蚀危害的使用寿命的公式。本文通过研究硫酸盐侵蚀机理及侵蚀过程,根据自然衰变方程,建立了混凝土抗硫酸盐侵蚀耐久寿命的预测模型,该模型能够很好地与试验数据吻合,更加贴切地模拟混凝土损伤的全过程,更好地预测混凝土的使用寿命。本文把硫酸盐侵蚀过程归结为“渗透—开裂—加速渗透—加速开裂”的网状扩散过程,提出寿命模型为指数分布,给出了指数的具体形式。并根据试验数据画出了各个影响因子的二维图像,建立了硫酸根质量浓度、水灰比、粉煤灰掺量、混凝土强度的影响函数,并综合考虑这些因素对混凝土耐久性的影响,得出了混凝土的硫酸盐损伤预测方程,根据龙岩至厦门铁路象山隧道工程所用混凝土配合比的数据及周围环境的实测数据,对该工程的使用年限进行了预测。其二,分析了混凝土的氯离子渗透试验方法,发现ASTMC1202试验方法虽然被广泛采用,但由于在试验过程中高电压会引起试块和溶液的温度上升,使得试验数据存在一定的误差。本人基于这方面的考虑,设计了适用于ASTMC1202法的温度控制系统。并开发了该系统所需的软件。该温度控制系统由“试验温度设定与显示模块”、“实时温度采样模块”、“制冷制热控制模块”三个部分构成。“试验温度设定与显示模块”的功能是由键盘输入预设温度并显示,然后将预设温度经数模转换器转换成电压信号Vs;“实时温度采样模块”的功能是用采样电阻获得实时温度对应的电压信号Vi;“制冷制热控制模块”的功能是比较电压信号Vs和Vi的差值,并将差值信号输入到控制芯片LTC1923来控制半导体制冷器。该差值的正负,控制着制热或是制冷,该差值的大小,控制着制热或制冷的功率,而当溶液温度与预设温度相等时系统不工作。该系统不仅能应用在混凝土的氯离子渗透试验之中,其他一些需要用到温度控制的试验也可使用,特别是需要精确控制温度的试验当中,因此适用范围较为广泛,有一定的应用前景。更多还原

【Abstract】 The research on the durability of concrete under the factors such as sulfate attack, chlorine ion penetration, carbonization etc, have become a hot problem of the domestic and international engineering field.This thesis mainly carried on a research to two among those’s problem.Firstly, though there are lots of domestic and international papers study on the damage caused by sulfate attack and gain some models about it, most of these models are from experience. Most of experience study can’t reflect the whole process of the damage caused by sulfate attack. And there still have no generally accepted formula which can predict the life of concrete under sulfate attack fast and precisely. According to the equation of natural disintegration and the analysis of the mechanism and the process of sulfate attack, this thesis establishes a prediction model of concrete’s service life in sulfate attack resistance. The prediction model can inosculate the trial data better, can reflect the whole process of the damage caused by sulfate attack more appropriately, and can predict the life of concrete preferably.This text sums up the whole process of the damage caused by sulfate attack to the reticulate diffusion course described as "permeate-open crack-the acceleration permeate-the acceleration open crack", puts forward the life model as a exponent distribution, and gives out the idiographic form of the exponent. Draw the two-dimensional pictures for each influence factor according to the experimented data, establish the influence function of sulfate ion solution concentration, cement ratio, coal ash content, concrete strength. And through consider these influence of the factor upon the concrete durability synthetically, a prediction equation of concrete’s service life in sulfate attack resistance were established. According to the ratio data of the concrete used in the tunnel project of Xiangshan in railway from Longyan to Shenzhen and the data of surroundings environment, this paper carries on an estimate to the concrete service life of that engineering.Secondly, analyse the chloride ion penetration test methods. Find the high voltage in the ASTMC1202 test process will lead temperature of the block and solution ascension. So it make the experiment data exist a certain error margin. Due to the consideration of this aspect, the temperature control system is designed to be applicable to ASTMC1202 methods. The software needed by this system is also been completed.There are three parts which contain"experiment temperature enactment and manifestation module", "real time temperature sample module", " refrigeration or calefaction control module"constitute the temperature control system. The function of "experiment temperature enactment and manifestation module" is to input the initial temperature from the keyboard and manifest it, then convert initial temperature into a voltage signal called Vs; The function of "real time temperature sample module" is to use a sample resistance to convert real time temperature into a voltage signal called Vi; The function of " refrigeration or calefaction control module" is to compare Vs with Vi, and send the difference to the control chip LTC1923 to control the Thermoelectric Coolers: the sign of the difference control refrigeration or calefaction, the size the difference control the power of refrigeration or calefaction. When the initial temperature equal the real time temperature, the system break down.The temperature control system not only can be used in the ASTMC1202 test, other experiment which need to control temperature also can use it, especially the experiments that need precision control of temperature. So its apply scope is more extensive and it have definite applied foreground.更多还原