考虑温度时变效应氯离子侵蚀混凝土的格子Boltzmann数值模型

Lattice Boltzmann Model of Chlorine Ion Erosion on Concrete Considering the Time Varying Effect of Temperature

对于长期暴露在氯盐环境下的混凝土结构,在外界温度影响下氯离子的侵蚀作用非常复杂,会影响钢筋锈蚀进程及其耐久性。为此,基于格子Boltzmann方法,采用双分布函数分别描述混凝土温度场和氯离子浓度场的演化过程,考虑外界温度的时变效应,建立氯离子侵蚀混凝土的数值模型。在此基础上,讨论水灰比、饱和度和昼夜温差等因素对氯离子侵蚀机制以及混凝土服役寿命的影响。研究表明:随着水灰比的增大,氯离子扩散系数逐渐增大,从而加剧了氯离子的侵蚀作用。混凝土饱和度越大,氯离子的扩散速率越快,从而导致混凝土的服役寿命缩短,当饱和度超过75%时,混凝土的服役寿命变化趋势逐渐趋于稳定。此外,昼夜温差越大,其对扩散系数的影响越显著,但总体而言,昼夜温差的变化对混凝土服役寿命的影响并不突出。

For the concrete structure exposed to chloride environment,the corrosion effect of chloride under the effect of external temperature is very complex,which affects the corrosion process of reinforcement and durability of concrete structures.Therefore,based on the lattice Boltzmann method,the double distribution functions are applied to describe the temperature evolution of concrete and the concentration evolution of chloride respectively,and a numerical model of chloride erosion concrete is established considering the time varying effect of temperature.On this basis,the chloride erosion mechanism and service life of concrete are discussed considering the effects of water-cement ratio,saturation and temperature difference between day and night.The results show that the diffusion coefficient of chloride increases with the increase of water-cement ratio,which intensifies the erosion effect of chloride.The higher the saturation of concrete is,the faster the diffusion rate of chloride is,which reduces the service life of concrete,and the trend tends to be stable when the saturation is more than 75%.In addition,the greater the temperature difference between day and night,the more significant the effect on the diffusion coefficient,but the effect of temperature difference between day and night on the service life of concrete is not obvious.