| 陈伟康,刘清风.干湿交替下混凝土中水分和多离子耦合传输的数值研究[J].水利学报,2021,52(5):622-632 |
| 干湿交替下混凝土中水分和多离子耦合传输的数值研究 |
| Moisture and multi-ions transport in concrete under drying-wetting cycles： a numerical study |
| 投稿时间：2020-12-31 |
| DOI：10.13243/j.cnki.slxb.20201099 |
| 中文关键词: 干湿交替 非饱和混凝土 水分 多离子 氯离子 电化学耦合 |
| 英文关键词: drying-wetting cycles unsaturated concrete moisture multi-species chloride electrochemical coupling |
| 基金项目:国家自然科学基金项目（51978396）；中国科协青年人才托举计划项目（2018QNRC001）；上海市“青年科技启明星计划”项目（19QA1404700）；流域水循环模拟与调控国家重点实验室开放基金项目（IWHR-SKL-201705） |
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| 中文摘要: |
| 干湿交替区混凝土结构的耐久性问题非常突出，非饱和混凝土中的氯离子传输在受到水分对流效应主导的同时，由于混凝土孔隙液中始终存在着多种自由离子，异种离子间的电化学耦合效应对氯传输的影响同样不可忽视。本文着重考虑多离子间电化学耦合效应和水分对流效应对氯离子传输的共同影响，建立经第三方实验验证的水分-多离子耦合传输模型。通过数值研究发现，干湿交替下多离子间电化学耦合效应会在孔隙液中产生时变的静电势，并对传输预测造成显著影响，10个干湿循环后考虑多离子传输的氯离子含量可达单一离子传输的1.26倍。同时发现干湿时间比的减小，干湿循环次数的增加，干燥过程水分边界饱和度的减小，三者均会放大电化学耦合效应对氯离子传输的影响。结果表明在干湿交替环境下，若仅考虑单一离子传输会导致对氯离子摄入量的预测偏低，致使混凝土的耐久性设计偏危险。 |
| 英文摘要: |
| The durability problems of concrete structures subjected to drying-wetting cycles are very prominent. Chloride transport in unsaturated concrete is mainly affected by the convection due to moisture transport. Meanwhile， since the concrete pore solution always contains multiple ionic species， the electrochemical coupling effect between different species on chloride transport is non-negligible. In this study， the effects of electrochemical multi-species coupling and convection are emphatically considered， and a coupled transport model of moisture and multiple ions in unsaturated concrete is established， which is verified by the third-party experiments. Though numerical study， it is found that the electrochemical coupling effect during drying-wetting actions would generate spatial-temporal electrostatic potential within concrete porous solution and markedly affects the prediction of ionic transport. After 10 times of drying-wetting cycles，the chloride content considering multi-species model is 1.26 times as compared to considering single-species model. The decrease of the time ratio of drying to wetting，the increase of the drying-wetting cycles，and the decrease of the water boundary saturation during the drying process could all enlarge the influence of the electrochemical coupling on chloride transport. The results show that considering a single-species transport will lead a lower prediction of chloride intake under drying-wetting conditions, which will result in a more dangerous durability design of concrete. |
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