Simulation and Analysis of Chloride Ion Diffusion in Cracked Concrete Based on Cellular Automata
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摘要:
为获得氯离子在开裂混凝土中的浓度分布以及分析裂缝形状、分布形式、偏转角度对混凝土中氯离子扩散效应的影响，根据氯离子在开裂混凝土中的扩散机理，利用元胞自动机和均匀化等效分析方法，建立了模拟开裂混凝土中氯离子扩散过程的元胞自动机模型，并利用数值试验对模型中元胞尺寸进行了优化. 研究结果表明：在不影响计算精度的情况下，为提高模型的计算效率，推荐采用元胞尺寸大小为0.5 mm；除个别数据外，模型模拟结果、试验结果与有限元分析结果吻合良好，最大偏差不超过10%；“V”形裂缝中氯离子浓度约为矩形裂缝的0.52倍；曲线形裂缝和折线形裂缝中氯离子浓度约为直线形裂缝的0.87倍和0.89倍；当裂缝偏转角从0° 分别增大至10°、20°、30° 时，裂缝端部氯离子浓度分别减小3.3%、21.9%、29.8%；裂缝对其周围氯离子扩散区域的影响范围与裂缝形状、分布形式和偏转角度无关，对裂缝周围氯离子扩散效应的影响主要集中在裂缝左右18 mm的范围内.
Abstract:In order to obtain the concentration distribution of chloride ions in cracked concrete and analyze the influence of crack shape, distribution form and deflection angle on the chloride ion diffusion in concrete, a cellular automata model for simulating the diffusion process of chloride ions in cracked concrete is established by using cellular automata and homogenization equivalent analysis methods according to the diffusion mechanism of chloride ions in cracked concrete; the cell size in the model is optimized by numerical experiments. The results show that the computational efficiency of the model can be improved with a high calculation accuracy when the cell size of is 0.5 mm. Except for individual data, the model simulation results are in good agreement with the test results and finite element analysis results, and the maximum deviation is no more than 10%. The chloride ion concentration in the "V" crack is about 0.52 times that in the rectangular crack. The chloride ion concentration in curved cracks and broken line cracks is about 0.87 times and 0.89 times that in linear cracks, respectively. When the fracture deflection angle increases from 0° to 10°, 20°, and 30°, the chloride ion concentration at the fracture end decreases by 3.3%, 21.9%, and 29.8%, respectively. The influence range of the crack on the chloride diffusion zone around the crack is independent of the shape, distribution form, and deflection angle of the crack. The influenced area is mainly concentrated on the range of about 18 mm perpendicular to the crack.
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Key words:
- cracks /
- cellular automata /
- durability /
- concrete /
- chloride ion
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图 3 氯离子浓度随扩散深度的变化规律
Figure 3. Variation law of chloride ion concentration with diffusion depth
图 4 利用CA模型获得的截面氯离子浓度分布结果
Figure 4. Chloride concentration distribution in section simulated by CA model
图 5 利用有限元法模拟的截面氯离子浓度分布结果
Figure 5. Chloride concentration distribution in the cross section simulated by finite element method
图 6 模型模拟结果与有限元解和试验值的比较
Figure 6. Comparison of model simulation results with element solutions and experimental values
图 7 模型模拟值与有限元解和试验值的比较
Figure 7. Comparison of model simulation values with finite element solutions and experimental values
图 8 不同裂缝形状下截面氯离子浓度模拟结果
Figure 8. Simulation results of chloride ion concentration in section under different crack shapes
图 9 截面氯离子浓度沿截面宽度的变化规律
Figure 9. Variation law of chloride ion concentration in cross section with cross section width
图 10 裂缝中心截面氯离子浓度随扩散深度的变化
Figure 10. Variation law of chloride ion concentration in central section of crack with diffusion depth
图 11 不同裂缝分布形式下截面氯离子浓度模拟结果
Figure 11. Simulation results of chloride ion concentration in cross section under different crack distribution forms
图 12 截面氯离子浓度沿截面宽度的变化
Figure 12. Variation law of chloride ion concentration in cross section with cross section width
图 13 裂缝中心截面氯离子浓度随扩散深度的变化
Figure 13. Variation law of chloride ion concentration in central section of crack with diffusion depth
图 14 不同裂缝偏转角下截面氯离子浓度模拟结果
Figure 14. Simulation results of chloride ion concentration in cross section under different fracture deflection angles
图 15 截面氯离子浓度沿截面宽度的变化
Figure 15. Variation law of chloride ion concentration in cross section with cross section width
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