Interfacial Micro-Mechanical Behavior of Discrete Fiber Reinforced Soil

摘要

Discrete fiber reinforcement is a newly developed technique to improve soil mechanical behaviour. The interfacial mechanical interactions between fiber reinforcement and soil play an important role in reinforcement benefit. The present work aims to study the interfacial micro-mechanical behavior of discrete polypropylene fiber (PP-fiber) reinforced natural soil and cement stabilized soil from qualitative and quantitative levels respectively. The evolution of the interfacial microstructure and fiber surface morphology in these soils were qualitatively characterized by using scanning electron microscopy (SEM). It was found that bond strength between Fibers and soil matrix, and the associated interfacial friction seems to be controlled by the soil properties and interfacial contact condition (microstructure, soil composition, fiber surface roughness etc.). In fiber reinforced raw soil, the fiber surface was attached by many clay minerals; in fiber reinforced cemented soil, the fiber surface was attached by hydration products of cement. Finally, an innovative apparatus was developed and the interfacial mechanical behaviour of fiber/soil was quantitatively analyzed by performing single fiber pull-out tests. It was found that the cement inclusion dramatically improved the interfacial friction and cohesion, and the interfacial shear strength between fiber and cemented soil was several times higher than that between fiber and natural soil.