温度与水力梯度作用下膨润土中水分迁移问题研究

温度与水力梯度下膨润土中水分迁移是保证核废料处置库长期安全有效运行的关键科学问题，然而目前关于膨润土渗透特性参数的测试仍未得到很好的解决。本项目针对膨润土中水分迁移问题，利用核磁共振分层CPMG技术，测得温度与水力梯度作用下低渗膨润土中水分迁移过程和组构变化；确定膨润土中水分迁移的机理与模型；基于核磁二维扩散理论和膨润土的二元结构提出膨润土考虑温度效应的渗透特性参数函数；通过膨润土中水分迁移数据与模型，利用hydrus反演得出膨润土的渗透特性参数；开发一套快速测试膨润土渗透特性参数的方法与技术。本项目的成功实施可为非饱和土和含冰量较高的冻土或含天然气水合物土等低渗介质水力特性的研究提供思路和分析方法，具有广阔的应用前景。

The moisture migration in bentonite under temperature and hydraulic gradient is the key to ensure the long-term safe and effective operation of nuclear waste repository. However, the problem has not yet been solved properly on the test of the hydraulic conductivity parameters of bentonite. The project focuses water migration in bentonite. With the application of layered CPMG technique in nuclear magnetic resonance, the process of water migration and fabric variation in bentonite under temperature and hydraulic gradient can be obtained. The mechanism and model for water migration in bentonite under temperature and hydraulic gradient can be proposed. The temperature function of hydraulic conductivity parameter for bentonite can be proposed based on the theory of two-dimensional nuclear magnetic relaxation dispersion (NMRD) and two levels of structure of bentonite. Hydraulic conductivity parameter of bentonite can be obtained by inversion of moisture migration and hydraulic constitutive models in bentonite with hydrus. A method and technology for rapid determining the hydraulic conductivity parameter of low permeability media can be developed. The successful implementation of this project can provide ideas and analysis methods for the study of hydraulic characteristics of low-permeability media such as unsaturated soils and frozen soils with high ice content or hydrate bearing soils, and has broad application prospects.