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非饱和土持水特性的滞回机理是土力学界的热点问题之一。将非饱和土看作“湿颗粒材料”并以“土-颗粒-系统”为视角更易认识其持水特性的滞回机理。以均匀湿颗粒材料为研究对象,用轴对称圆锥形孔隙内水分的充填和排出过程来模拟边界增、减湿过程,提出一种物理模型以描述其滞回特性的物理内涵,并利用已有文献中3种砂土和2种含黏砂土的持水试验结果验证了该模型在表征均匀湿颗粒材料边界滞回持水曲线时的有效性。该模型的优点在于不仅对同种均匀湿颗粒材料滞回的边界减、增湿持水曲线可采用同一组具有物理意义的参数模拟,而且可反映孔隙水内封闭气泡对持水曲线的影响。
Hysteresis mechanism of unsaturated soil water holding properties is one of the hot issues in the field of soil mechanics. The unsaturated soil is considered as “wet granular material” and the hysteresis mechanism of water-holding characteristics is more easily recognized from the perspective of “soil-grain-system”. Taking the uniform wet granular material as the research object, the process of the boundary adding and dehumidifying is simulated by filling and discharging the moisture in the axisymmetric conical pore. A physical model is proposed to describe the physical connotation of the hysteresis characteristics. The water-holding test results of three kinds of sand and two kinds of clay-containing sand in the literature verify the effectiveness of the model in characterizing the hysteresis retention curve of homogeneous wet particle materials. The model has the advantage of not only reducing the hysteretic boundary of the same kind of uniform wet granular material, but also using the same set of physical parameters to simulate the water-holding capacity curve, which can reflect the influence of the closed bubbles in the pore water on the water holding curve.