A soil water retention equation of bentonites used in deep geological repositories

The Fredlund-Xing (FX) model was chosen to develop the proposed equation. Pictures and parameters-fitting producted by OriginPro. 1. the comparisons between all parameters of the FX model and characteristic of experimental values on the water retention behavior of confined bentonite samples were found. 1.1 because residual suction only influences on correction factor of the FX model, the relationship between correction factor C(ψ) and suction ψ was conducted and shown in Fig.2. 1.2 Fig.3 shows the fitting curve at 20 °C along with the experimental values of saturated water content as a function of dry densities for compacted GMZ01 bentonite. 1.3 Fig.4(a) has given the fitting results along with the experimental values of air-entry values to total void ratios on compacted samples for three popular types of bentonite at the room temperature. 1.4 n_f and m_f influence on SWRCs of the FX model separately. 2. The proposed water retention equation is validated against experimental datum from literatures on three popular types of bentonite (GMZ01 bentonite, FEBEX bentonite, and MX-80 bentonite).本研究选用Fredlund-Xing（FX）模型构建所提出的水分特征方程。所有图像与参数拟合结果均由OriginPro生成。 1. 针对受限膨润土试样的水分特征行为，开展了FX模型全参数与实验值特征的对比分析。 1.1 由于残余吸力仅对FX模型的修正因子产生影响，因此构建了修正因子C(ψ)与吸力ψ之间的关系，结果如图2所示。 1.2 图3展示了20℃条件下的拟合曲线，以及压实GMZ01膨润土的饱和含水率随干密度变化的实验值。 1.3 图4(a)给出了室温下三种常用膨润土压实试样的进气值随总孔隙比变化的拟合结果与实验数据。 1.4 参数n_f与m_f分别对FX模型的土壤水分特征曲线（SWRC, Soil-Water Retention Curve）产生影响。 2. 针对GMZ01膨润土、FEBEX膨润土与MX-80膨润土三种常用膨润土的文献实验数据，对所提出的水分特征方程开展了验证工作。