周期性温湿度作用下混凝土内部温湿度场的模拟计算

发布时间：2018-05-27 21:10

本文选题：混凝土 + 多孔介质　；参考：《安徽工业大学》2014年硕士论文

【摘要】：混凝土的体积稳定性也是影响混凝土材料及结构耐久性的主要原因，混凝土变形开裂后渗透性增加而使碳化、化学侵蚀、钢筋锈蚀等耐久性劣化过程更易进行，，严重危害混凝土耐久性及结构使用寿命。实际工程结构混凝土的变形开裂是环境温湿度变化和结构外荷载共同作用的结果，对周期性温湿度作用下混凝土内部温湿度场的模拟计算研究具有重要的实际意义。本文围绕周期性温湿度作用下混凝土内部温湿度场的模拟计算，综合利用多孔介质力学、复合材料力学混凝土细观力学均匀化方法，从水泥石-混凝土材料-混凝土构件等不同尺度层次上，在水泥石内部湿热传输机理及模型、混凝土细观力学变形机理及湿热耦合变形数值模拟等方面，对湿-热-力耦合作用下混凝土变形开裂多尺度模拟的相关机理、模型和数值模拟方法进行研究。根据水泥石内部典型孔分布情况，认为在分析水泥石内部湿热传输时必须考虑湿度的Knudsen扩散，并分析了考虑Knudsen扩散的内部湿传输机理，建立了相应的湿传输模型；根据混凝土的三相（水泥石-过渡区-集料）组成模型、水泥石应力应变关系，利用复合材料力学原理研究了混凝土的应力应变关系；利用细观力学均匀化方法，将混凝土的湿热物理参数、基本力学参数看做均匀分布并通过水泥石、集料的相关参数进行对算确定；参考热膨胀系数的定义，考虑到实际应用的方便性，初步提出了混凝土湿膨胀系数的概念、定义和理论计算公式的推导；基于多孔介质湿热传输原理和水泥石湿热传输模型，研究了混凝土材料湿热耦合变形数值模拟方法，并通过算例分析进行了验证；对实际环境温湿度变化特点、混凝土在实际温湿度环境和受力条件下的变形开裂机理进行了分析，并对混凝土构件湿-热-力耦合变形开裂数值模拟方法和可用软件等进行了讨论和初步研究。研究结果表明：考虑Knudsen扩散影响的水泥石湿热传输机理更为合理；提出的水泥基复合材料湿膨胀系数和理论计算公式及反演法确定方法具有可行性和实用性；基于多孔介质湿热传输原理的混凝土湿热耦合变形模拟计算能够反映混凝土内部的湿热耦合效应，可以用于混凝土材料变形模拟分析；实际工程结构混凝土变形开裂是湿-热-力耦合作用的结果，且由于实际环境温湿度变化的类周期性而存在类似疲劳损伤的作用；宜选用适合多物理场耦合分析的COMSOL Multiphysics软件对湿-热-力耦合作用下混凝土变形开裂行为进行数值模拟。有关湿膨胀系数、湿-热-力耦合作用下混凝土变形开裂机理等方面有待进一步研究完善。
[Abstract]:The volume stability of concrete is also the main reason affecting the durability of concrete materials and structures . The durability deterioration process such as carbonation , chemical attack and reinforcement corrosion is more apt to be carried out after the concrete deformation and cracking , and the durability and service life of concrete are seriously damaged . The deformation cracking of concrete in practical engineering structure is the result of environmental temperature and humidity change and structural outer load , and it is of great practical significance for simulating calculation of temperature and humidity field in concrete under the action of periodic temperature and humidity .

In this paper , the relative mechanism , model and numerical simulation method of concrete deformation cracking multi - scale simulation under the action of wet - heat - force coupling are studied by simulating calculation of the temperature and humidity field in concrete under the action of periodic temperature and humidity , and the mechanism , model and numerical simulation method for the multi - scale simulation of concrete deformation cracking under the action of wet - heat - force coupling are studied .
According to the three - phase ( cement - transition zone - aggregate ) composition model of concrete , the stress - strain relation of cement stone is studied , and the stress - strain relation of concrete is studied by using the mechanics principle of composite material ;
The wet and heat physical parameters and basic mechanical parameters of the concrete are uniformly distributed and determined by the relevant parameters of the cement stone and aggregate by using the uniform method of the meso - mechanical homogenization ;
Referring to the definition of thermal expansion coefficient , considering the convenience of practical application , the concept , definition and calculation formula of concrete moisture expansion coefficient are preliminarily proposed .
Based on the principle of wet heat transfer of porous medium and the model of wet heat transfer of cement stone , the numerical simulation method of damp - heat coupling deformation of concrete is studied , and the example analysis is verified .
The deformation cracking mechanism of concrete under actual temperature and humidity environment and stress condition is analyzed , and the numerical simulation method and available software of wet - heat - force coupling deformation cracking of concrete members are discussed and studied .

The results show that the mechanism of wet heat transfer considering Knudsen diffusion is more reasonable .
The proposed method for determining the coefficient of wet expansion and theoretical calculation of the cement - based composite is feasible and practical .
The simulation calculation of concrete damp - heat coupling deformation based on the principle of wet heat transfer of porous medium can reflect the damp - heat coupling effect inside the concrete , and can be used for the simulation analysis of concrete material deformation ;
The concrete deformation cracking of the practical engineering structure is the result of the wet - heat - force coupling effect , and the effect of similar fatigue damage exists due to the periodicity of the temperature and humidity change of the actual environment .
The crack behavior of concrete under the action of wet - thermal - force coupling is numerically simulated by COMSOL Multiphysics software , which is suitable for multi - physical field coupling analysis .
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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