This paper presents a trans-scale finite element model based on hydraulic-thermal-mechanical coupling equations of porous medium to simulate the behavior of concrete during freezing and thawing. Unlike previous models that regard concrete as homogeneous material, this paper aims to establish a macro-size concrete model with detailed micro-structure, the aggregates (mm) and air voids (μm) are randomly generated by the Monte Carlo method, and the interfacial transition zones (μm) with random thickness are built around the aggregates. The capillary pores (nm) of concrete is expressed by the relationship between the percentage of frozen ice and the radius of capillary pore. The simulation results reveal the mechanism of air voids protecting the concrete from freezing and thawing damage, and the mechanical field shows the freezing and thawing damage occurs preferentially at the interfacial transition zone, because the stress concentration due to the irregular distribution of aggregates and water resistance of aggregates. The temperature boundary conditions were also varied to study the influence of the temperature change rate on hydrostatic pressure and volume stress. The effect of the cement paste's pore structure, including the spacing of air voids, on the ability of concrete to resist freezing and thawing is presented.

本文提出了一种基于多孔介质水热力耦合方程的跨尺度有限元模型，以模拟混凝土在冻融过程中的行为。与以前的将混凝土视为均质材料的模型不同，本文旨在建立具有详细微观结构的宏观混凝土模型，通过蒙特卡洛方法随机生成骨料（mm）和气孔（μm），以及界面聚集体周围建立了具有随机厚度的过渡区（μm）。混凝土的毛细孔（nm）由冷冻冰的百分比和毛细孔半径之间的关系表示。仿真结果揭示了气孔保护混凝土免受冻融破坏的机理，机械场表明，冻融破坏优先发生在界面过渡区，这是由于骨料的不规则分布和骨料的耐水性引起的应力集中。还改变了温度边界条件，以研究温度变化率对静水压力和体积应力的影响。提出了水泥浆孔隙结构（包括空隙的间距）对混凝土抗冻融能力的影响。还改变了温度边界条件，以研究温度变化率对静水压力和体积应力的影响。提出了水泥浆孔隙结构（包括空隙的间距）对混凝土抗冻融能力的影响。还改变了温度边界条件，以研究温度变化率对静水压力和体积应力的影响。提出了水泥浆孔隙结构（包括空隙的间距）对混凝土抗冻融能力的影响。