高导热性混凝土细观数值模拟与工程应用

发布时间：2018-06-21 23:19

本文选题：桥梁结构 + 有效导热系数　；参考：《长安大学》2017年硕士论文

【摘要】：工程中常用混凝土的有效导热系数较低,在太阳辐射、气温骤变等环境因素的影响下,将在结构内部产生较大的温度效应,极有可能导致混凝土结构发生开裂。而提高混凝土的有效导热系数是减小混凝土结构温度效应和防止混凝土桥梁结构出现温度裂缝的有效方法。本文围绕高导热性混凝土细观数值模拟与工程应用开展如下研究:(1)从混凝土材料的细观结构特征出发,提出一种任意级配混凝土有效导热系数的细观数值计算方法及其考虑孔隙的修正方法,并根据已有试验结果验证了两种方法正确性,结果表明两者均能用于混凝土导热系数的预测,且后者精度更高;同时,提出了骨料二维级配概念,并证明二维级配曲线存在,且与三维级配曲线一一对应。(2)基于任意级配混凝土细观数值模型,提出一种任意级配钢纤维混凝土细观数值模型的建立方法,分别研究了钢纤维掺量、铁矿砂对普通细集料的置换率、骨料类型及骨料体积分数对混凝土有效导热系数的影响,并给出提高混凝土导热系数的相关建议。(3)利用太阳物理学原理及气象资料构造边界条件,基于传热学和泛函极值算法推导了二类、三类耦合边界下非稳态温度场的计算公式,系统说明了混凝土桥塔非线性瞬态温度场的计算方法,并根据两桥塔温度场实测结果验证了该方法的正确性。同时,分别研究了实心截面和空心截面桥塔日照温度分布特点。(4)以混凝土桥塔为例,利用混凝土桥塔非线性瞬态温度场的计算方法与高导热性混凝土细观数值模拟的相关结论,研究了提高混凝土有效导热系数对桥塔结构温度效应的影响,为高导热性混凝土在工程中的应用提供依据。
[Abstract]:The effective thermal conductivity of concrete in common use in engineering is relatively low. Under the influence of environmental factors such as solar radiation and sudden change of temperature, there will be a large temperature effect in the structure, which may lead to the cracking of concrete structure. Increasing the effective thermal conductivity of concrete is an effective method to reduce the temperature effect of concrete structure and prevent the temperature crack of concrete bridge structure. In this paper, the following researches have been carried out around the meso-numerical simulation and engineering application of high thermal conductivity concrete: (1) starting from the characteristics of meso-structure of concrete materials, A mesoscale numerical method for calculating the effective thermal conductivity of concrete with arbitrary gradation and a modified method considering pores are presented. The correctness of the two methods is verified by the experimental results. The results show that both of them can be used to predict the thermal conductivity of concrete, and the precision of the latter is higher. At the same time, the concept of two-dimensional gradation of aggregate is proposed, and the existence of two-dimensional gradation curve is proved. And corresponding to the three-dimensional gradation curve. (2) based on the mesoscale numerical model of concrete with arbitrary gradation, a method of establishing meso-numerical model of steel fiber reinforced concrete with arbitrary gradation is proposed, and the content of steel fiber is studied respectively. The effect of iron ore on the replacement rate of ordinary fine aggregate, the type of aggregate and the volume fraction of aggregate on the effective thermal conductivity of concrete, Some suggestions for improving the thermal conductivity of concrete are given. (3) based on the theory of solar physics and meteorological data, the calculation formulas of unsteady temperature field under two and three kinds of coupled boundaries are derived based on heat transfer and functional extremum algorithm. The calculation method of nonlinear transient temperature field of concrete bridge tower is systematically explained, and the correctness of the method is verified by the measured results of temperature field of two towers. At the same time, the characteristics of sunshine temperature distribution of solid section and hollow section tower are studied respectively. (4) taking concrete bridge tower as an example, using the calculation method of nonlinear transient temperature field of concrete bridge tower and the relevant conclusions of meso-numerical simulation of high thermal conductivity concrete. The influence of increasing the effective thermal conductivity of concrete on the temperature effect of bridge tower structure is studied, which provides the basis for the application of high thermal conductivity concrete in engineering.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

【相似文献】