Micromechanical description of adsorptive-capillary stress in wet fine-grained media

The aim of this paper is to investigate the effect of an adsorbed water layer on the mechanical behavior of finegrained 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 YoungLaplace 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.

Automated summary

This paper investigates the effect of an adsorbed water layer on the mechanical behavior of fine-grained wet granular materials, revealing that adsorbed layers can significantly increase interparticle cohesive force and rupture distance, especially under high suction conditions.