Toughening effect and mechanism of rice straw Fiber-reinforced lime soil

Lime-stabilized soil used for subgrade is prone to brittle damage under loading because of low toughness. Based on this phenomenon, the toughening effects of anticorrosive rice straw fibers on the lime-stabilized soil and its internal mechanism have been studied in this paper. Different fiber contents (0.2 wt%, 0.6 wt%, 1.0 wt%) and fiber lengths (0-10 mm, 10-20 mm, 20-30 mm) were studied. Three-point bending tests, unconfined compressive strength tests and triaxial compression tests were conducted on the rice straw fiber-reinforced lime soil. Energy absorption, deformation index, and brittleness index were evaluated under flexure, compression, and shear. The toughness change from energy, deformation, and strength was studied based on these. The toughening mechanism of fiber reinforcement was analyzed from the mechanism of fiber-soil interaction, the energy absorption threshold of the damage process, the damage pattern of specimens and the length of the crack propagation path. The results showed that with the increase in fiber content and fiber length, the energy absorption and deformation index of the damage process increased while the brittleness index decreased. The brittle damage pattern was improved, and the toughness increased. The fibers connect the soil particles on both sides of the fracture surface through the bridging effect, form a three-dimensional reinforcement network to restrict the soil particle movement and consume a lot of energy during the interaction with soil, which causes the increase in the energy absorption threshold of soil. Thus, the toughness of the lime-stabilized soil is improved.