Abstract: Rubber is widely used in civil engineering as a material with high elasticity, low density and high durability. In this study, the shear stress-displacement response of the saturated rubber fiber reinforced soil with vertical stress of 50, 100, 200 and 400 kPa and rubber fiber content of 0%, 5%, 7%, 10% and 15% was studied. The test results show that: (1) rubber fiber reinforced expansive soil can significantly reduce the vertical displacement during soil consolidation. (2) ESR generally achieves peak shear strength at a shear displacement of 2 mm and converts from strain softening to strain hardening as the rubber fiber content increases. (3) Rubber fiber can significantly increase the cohesion of expansive soil, but the change of internal friction angle is not obvious. (4) The stress ratio Rτult parameter was introduced to describe the relationship between shear strength and fiber content and vertical stress, and it was found that fibers can improve the shear strength of reinforced soil.

Key words: Direct Shear Tests, Expansive Soils, Rubber Fiber, Stress Ratio, Shear Strength