This study investigates experimentally the water retention behavior of granular soils from saturation to oven-dry state. The soil–water retention curve (SWRC) tests were conducted on a well-graded sand with clay using tensiometer and chilled-mirror hygrometer techniques. The soil samples were statically compacted at various water contents to different initial densities. The results showed that individual linear segments in the log–log graph could characterize the desorption process of capillary and adsorption water. A novel water retention model in a simple mathematical form was developed by conceptualizing the total water content as the sum of the suction-dependent capillary and adsorption components. The model parameters possess an unambiguous physical meaning. They can be easily calibrated based on the graphical properties of the test data using simple linear regression, which is a significant advantage over conventional SWRC models. The model was validated using the water retention data of the tested soil in this study and the available data of granular soils in the literature. The reproduced curves agree well with the experimental results. This study also analyzed the influence of compaction water content, initial density, and clay content on the capillary and adsorption components of the water retention curve. Additionally, the proposed framework provides a quick approximation method for the adsorption capacity, which plays an essential role in assessing the effective stress and the simulation of liquid film flow in unsaturated granular soils.

本研究通过实验研究了颗粒土壤从饱和状态到绝干状态的保水行为。使用张力计和冷镜湿度计技术，在级配良好的粘土砂上进行了土壤保水曲线（SWRC）测试。将不同含水量的土壤样品静态压实至不同的初始密度。结果表明，双对数图中的各个线性段可以表征毛细管和吸附水的解吸过程。通过将总水含量概念化为吸力相关的毛细管和吸附成分的总和，开发了一种简单数学形式的新颖保水模型。模型参数具有明确的物理意义。它们可以使用简单的线性回归根据测试数据的图形属性轻松校准，这比传统的 SWRC 模型具有显着优势。使用本研究中测试土壤的保水数据和文献中颗粒土壤的可用数据对该模型进行了验证。再现的曲线与实验结果非常吻合。本研究还分析了压实含水量、初始密度和粘土含量对保水曲线的毛细管和吸附分量的影响。此外，所提出的框架提供了吸附能力的快速近似方法，这在评估非饱和颗粒土中的有效应力和液膜流模拟中发挥着重要作用。