Abstract: In recent years, the number of waste tires has continued to increase, and finding a reasonable way to dispose of waste tires has become an urgent problem. To find a way to deal with a large number of waste tires, this paper investigates the feasibility of using rubber fibers to improve expansive soil. Firstly, Direct shear tests were employed to investigate the effects of different rubber fiber contents on the mechanical characteristics of expansive soil. Then, a strength prediction model for rubber fiber reinforced expansive soil was developed based on the discrete model. The results shows that there is an enhancement in the strength of rubber fiber reinforced expansive soil with 5% and 10% fiber content compared to expansive soil, with the maximum strength enhancement at 10% rubber fiber content. Rubber fibers enhance the cohesion of expansive soil and have little effect on the internal friction angle. When the rubber fiber content is 15%, the rubber fibers adhere to each other and the fibers cannot be completely covered by the soil particles, which produces faults in the soil particles and thus reduces the soil strength. A strength prediction model for rubber fiber-reinforced expansive soil is proposed based on the discrete model, which effectively predicts the shear strength of rubber fiber-reinforced expansive soil.

Key words: expansive soil, rubber fiber-reinforced, direct shear, shear strength, strength prediction model