膨润土类工程屏障溶质耦合运移理论研究进展

Research Progress on Coupled Solute Transport Theory in Bentonite-Based Engineering Barriers

摘要:

详细梳理了等温溶质耦合运移（ICST）理论研究成果，并基于COMSOL数值软件，比较了不同模型的溶质通量模拟结果。研究结果表明：ICST模型主要包括反扩散（CD）模型和盐扩散（SD）模型，两者的通量模拟结果基本一致，但后者在理论上更为准确。对流—扩散（AD）模型高估了溶质运移通量，而考虑限制性扩散后，AD模型（ADC）与ICST模型的模拟结果差异显著缩小。在实际应用中，建议结合现场工况合理使用SD模型和ADC模型。鉴于工程屏障近场环境的复杂性，阐明非等温、非饱和及土体变形作用下溶质耦合运移机制，并构建准确反映模型参数随浓度和温度变化的土体热—水—力—化溶质耦合运移模型，应是今后的研究重点。

Abstract:

This paper provides a detailed review of research on isothermal coupled solute transport （ICST） theory and， and compares solute flux predictions from different theoretical models using COMSOL numerical software. The results show that ICST models include both the counter-diffusion （CD） model and the salt-diffusion （SD） model. Although the flux predictions of the CD and SD models are basically consistent， the SD model is theoretically more accurate. The advection-diffusion （AD） model overestimates solute transport. However， when the restricted diffusion is considered， the flux predictions obtained by the AD model substantially diminish the discrepancies observed with the ICST models. In practical applications， it is recommended to appropriately use the SD model or ADC model considering site-specific conditions. Given the complexity of the near-field environments in engineering barriers， future theoretical research should focus on elucidating coupled solute transport mechanisms under non-isothermal， unsaturated， and soil deformation conditions， and on developing a fully coupled thermo-hydro-mechanical-chemical solute transport model that accurately reflects the effects of concentration and temperature on model parameters.