Shear Strength and Mesoscopic Characteristics of Basalt Fiber–Reinforced Loess after Dry–Wet Cycles

Abstract

Frequent dry–wet cycles induced uneven settlement and slope failure of transportation infrastructures in the Loess Plateau of China. Fiber reinforcement provides a method for solving these problems. In this study, a digital image–based triaxial shear test system was adopted through which to study the dry–wet action on mechanical behavior and failure mode of basalt fiber–reinforced loess. The apparent cracks and mesostructure of fiber-reinforced loess after dry–wet cycles were observed by digital camera and X-ray computed tomography technique (CT). Results show that the shear strength of fiber-reinforced loess decreases after dry–wet cycles, whereas it shows inverted U-shaped variations with fiber content, with the optimal resistance to dry–wet action at 0.6%. Compared with unreinforced loess, the samples with fiber reinforcement show fewer cracks, implying the effectiveness of fibers in inhibiting initiation and propagation of apparent cracks. The failure mode changes from brittle shear failure to overall bulging after fiber addition. The CT scan results showed that the fibers inhibited the generation and propagation of microcracks, and the damage mainly occurred in the early stage of the dry–wet cycles.