Unconfined compression behavior of basalt fiber-reinforced loess based on digital image correlation and scanning electron microscope

摘要

Basalt fiber is a promising reinforcement agent for loess engineering. In this study, unconfined compressive tests facilitatedwith the digital image correlation (3D-DIC) method were carried out on basalt fiber-reinforced loess to obtain the deformationimages and surface strain fields at different loading moments. The reinforcement mechanism of samples with differentfiber contents and fiber lengths was interpreted from the microstructure obtained by scanning electron microscope (SEM).Results showed that the stress-strain curves of fiber-reinforced samples are all strain-softening. The curves of unconfinedcompressive strength (UCS) versus fiber length or fiber content manifest an overall inverted U-shaped pattern. The optimalreinforcement effect was observed at a fiber content of 0.6 and a fiber length of 12 mm. The failure strain, plasticityratio, and energy absorption capacity of samples vary with fiber content or fiber length like that of the UCS. Fracture ofunreinforced loess was noted, characterized by brittle failure, while the reinforced loess exhibits bulging failure with ductilecharacteristics. The surface strain field shows that the maximum axial strain varies with fiber content and fiber length incontrast to the strength. The deformation of the sample is more uniform under the optimal fiber condition, and the effect offiber content is significantly greater than that of fiber length. SEM images indicate that the fibers are more uniformly distributedin the soil at lower fiber contents and smaller fiber lengths. Otherwise, significant entanglement or agglomerationwill occur, resulting in the creation of weak surfaces in the soil.