| 联合机制下黏土垫层多离子扩散模型 |
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| 引用本文： | 张志红,韩林,吕清硕.联合机制下黏土垫层多离子扩散模型[J].岩土力学,2022,43(2):539-548. |
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| 作者姓名： | 张志红 韩林 吕清硕 |
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| 作者单位： | 北京工业大学 城市与工程安全减灾教育部重点实验室，北京 100124 |
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| 基金项目： | 国家自然科学基金面上项目(No.51678012)。 |
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| 摘 要： | 扩散是工程领域中的一种重要现象，尤其是针对填埋场底部的压实黏土垫层。扩散过程受多种因素影响，如离子种类、离子价态和离子浓度等，因此建立准确的扩散模型对填埋场垫层系统设计和评估具有极其重要的意义。引入简化的Guntelberg活度系数表示真实溶液与理想溶液浓度值的偏差，采用化学势和扩散势共同表征多离子扩散的驱动力，并考虑黏土介质特有的半透膜性能对离子扩散规律的影响，建立了复杂机制联合作用下多组分并存时离子在黏土垫层中的扩散模型。采用多物理场仿真软件COMSOL Multiphysics对所建扩散模型进行数值求解，结果表明，黏土半透膜效应、溶液非理想性和扩散势均显著影响多离子扩散行为，考虑黏土半透膜效应及溶液非理想性条件下，多离子扩散进程明显减缓，考虑扩散势时，阳离子扩散速度显著提高。复杂机制联合作用下，多离子扩散规律并非单一影响机制的简单叠加，各机制之间相互制约共同影响多离子扩散行为。
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| 关 键 词： | 多离子 活度系数 扩散势 半透膜效应 扩散 |
| 收稿时间： | 2021-08-10 |
| 修稿时间： | 2021-11-30 |
A multi-ion diffusion model through clay barriers under combined action |
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| ZHANG Zhi-hong,HAN Lin,Lü Qing-shuo.A multi-ion diffusion model through clay barriers under combined action[J].Rock and Soil Mechanics,2022,43(2):539-548. |
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| Authors: | ZHANG Zhi-hong HAN Lin LÜ Qing-shuo |
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| Institution: | Key Laboratory of Urban Security & Disaster Engineering, Ministry of Education, Beijing University of Technology, Beijing 100124, China |
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| Abstract: | Diffusion is an important phenomenon that governs contaminant transport through compacted clay liner at the bottom of landfill.The diffusion process is influenced by many factors, i.e., type, valence and concentration of ions. Therefore, an accurate diffusion model is of great importance for the design of liner system of landfill. The simplified Guntelberg activity coefficient was introduced to indicate concentration difference between ideal solution and actual solution. The driving force of diffusion usually considered combined action of chemical and diffusion potential. The semipermeable membrane effect of clay was considered. A diffusion model describing simultaneous movement of multi-ions through clay barrier was proposed. Moreover, the multi-physical field simulation software COMSOL Multiphysics was employed for conducting simulations for the proposed diffusion model. The results indicate that the factors such as solution non-ideality, diffusion potential, and semipermeable membrane effect of clay play an important role in the diffusion process of multiple ions. A remarkable retarded behavior was captured, when the solution non-ideality or semipermeable membrane effect was considered in the proposed model. Further, an accelerating effect on cations was observed taking diffusion potential into consideration. The multi-ion diffusion process under combined action is not a simple superposition of single influence mechanism, but rather, each mechanism restricts each other and affects the multi-ion diffusion behavior. |
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| Keywords: | multiple ions activity coefficient diffusion potential semipermeable membrane effect diffusion |
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