孔隙结构演变对混凝土电化学修复过程影响数值模拟研究

NUMERICAL SIMULATION STUDY OF EFFECT OF PORE STRUCTURE EVOLUTION ON ELECTROCHEMICAL REHABILITATION FOR CONCRETE

电化学修复过程中混凝土孔隙结构会发生改变,离子传输过程受到影响。本文基于物质守恒方程、Nernst-Planck方程与高斯静电理论,在混凝土是均匀单一介质的假定下,考虑了孔隙率对离子扩散系数的影响,建立了孔隙修正的均质化电化学修复模型。分别采用均质化模型与未考虑孔隙变化模型模拟了30d的电化学除氯过程,并与试验结果比较,对比了模型的优劣性。结果表明,考虑孔隙率改变对电化学修复数值模拟结果影响显著;混凝土保护层中间区域受到的影响大于辅助阳极与阴极钢筋附近区域;考虑孔隙变化影响后阴极数值模拟与试验误差减小但辅助阳极附近误差反而增大。

The pore structure in concrete would change during the electrochemical rehabilitation process, affecting the ions transport process. Based on the mass conservation equation, Nernst-Planck equation and Gauss＇ s electrostatic theory, under the assumption that concrete is an uniform single-phase medium, the modified homogenization model was established considering the porosity effect. The electrochemical rehabilitation process was simulated for 30 days with homogenization model and unmodified model respectively and the differences between simulation results and experimental results were compared. The results showed that the effect of porosity change on the numerical simulation results of electrochemical rehabilitation was significant. The influence in the middle area of the concrete cover was greater than that near the anode and cathode. The error at the cathode is smaller in homogenization model than that in unmodified model while the results were on the contrary at the anode.