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根据Fick第二定律建立了硫酸根离子在混凝土中的非稳态扩散反应方程,利用有限差分法求解该方程以获得硫酸根离子在混凝土中的浓度分布规律。根据硫酸根离子与混凝土中铝酸钙盐之间的化学反应所生成钙钒石的数量,给出了钙钒石生成过程中的混凝土膨胀应变计算公式,并由混凝土本构关系计算相应的膨胀应力,以评估混凝土是否开裂破坏。最后,通过数值仿真,模拟浸泡在2%Na2SO4溶液里的混凝土板内的硫酸根离子扩散过程、膨胀应变及应力变化、开裂破坏等全过程。结果表明:所提出的分析方法可定量地描述硫酸盐侵蚀下的混凝土损伤破坏规律。
According to Fick’s second law, the unsteady diffusion reaction equation of sulfate ion in concrete was established. The equation was solved by finite difference method to obtain the concentration distribution of sulfate ion in concrete. According to the quantity of the erbasite formed by the chemical reaction between the sulfate ion and the calcium aluminate in the concrete, the formula for calculating the expansion strain of the concrete during the formation of the erbasite is given and the corresponding expansion is calculated from the constitutive relation of the concrete Stress to assess whether the cracking of concrete cracking. Finally, numerical simulation is used to simulate the whole process of sulfate ion diffusion, expansion strain and stress change, cracking and so on in the concrete slab immersed in 2% Na2SO4 solution. The results show that the proposed method can quantitatively describe the damage damage of concrete under sulfate attack.