X-ray computed tomography imaging of fibre-reinforced clay subjected to triaxial loading

The strength evolution of fibre-reinforced soils has often been examined experimentally using conventional soil testing techniques and numerically by modelling the physico-mechanical behaviour of the soil-fibre interface. Although fibre reinforcement provides a surplus strength to the soil, its real strength contribution is highly dependent on the re-orientation of fibres within the spatial domain of the compacted soil under loading. In this study, a series of unconsolidated undrained triaxial tests were carried out on miniature fibre-reinforced clay samples and the 3D architecture of the fibres before and during the loading was visualised using an intensive image processing technique. This research for the first time investigates the mechanism of fibre re-orientation, spatial distribution, displacement and tortuosity in a randomly fibre-reinforced clay at different stages of loading using an advanced X-ray computed tomography (CT) imaging facility. The results showed a high degree of anisotropic distribution of fibres (i.e. both in spatial location and angles in XZ/XYplanes) that is further intensified upon loading.