The aim of this paper is to investigate the effect of an adsorbed water layer on the mechanical behavior of fine-grained wet granular materials in the pendular regime with isolated capillary liquid bridges. The adsorbed water forms a thin liquid film tightly bound to a particle’s surface equilibrated by a so-called “disjoining pressure”. In a stress transmission analysis, this disjoining pressure concept is embedded in the so-called Augmented Young-Laplace equation to account for thin film interfacial interactions. Using a homogenization technique for upscaling the micro-scale physics, an adsorptive-capillary stress tensor is derived whose discrete representation reveals a new interparticle cohesive force. In the presence of adsorbed layers, it is shown that the new liquid bridge profile, as numerically solved from the Young-Laplace equation, leads to a higher cohesive interparticle force and rupture distance. The proposed adsorptive-capillary stress tensor is further implemented within a discrete element modeling framework. As such, the evolutions of microstructure, stress tensors, and shear strength are illustrated during suction-controlled triaxial simulations. Our numerical results demonstrate that adsorbed layers have a notable effect on the mechanical behavior of fine-grained materials, particularly at higher suctions.

本文的目的是研究吸附水层对细粒湿颗粒材料在具有孤立毛细管液桥的摆动状态下的力学行为的影响。被吸附的水形成一层薄薄的液膜，紧密结合在通过所谓的“分离压力”平衡的颗粒表面。在应力传递分析中，这种分离的压力概念被嵌入到所谓的增强杨拉普拉斯方程中，以解释薄膜界面相互作用。使用均质化技术放大微观物理，推导出吸附毛细管应力张量，其离散表示揭示了新的粒子间内聚力。在存在吸附层的情况下，表明新的液桥剖面，如从杨拉普拉斯方程数值求解的，导致更高的内聚力和破裂距离。建议的吸附毛细管应力张量在离散元素建模框架内进一步实施。因此，在吸力控制的三轴模拟中说明了微观结构、应力张量和剪切强度的演变。我们的数值结果表明，吸附层对细粒材料的机械性能有显着影响，尤其是在较高吸力下。